Migrate convertible to foldable

[irwiss]

Summary

Bugfixes "Migrate convertible stuff to foldable"

Purpose of change

Fixes #48113
Fixes #46752
Fixes #28976
Fixes #39399
Fixes #51005

Describe the solution

Patch converts all "convertible" items and vehicles to their to "generic" foldable equivalents.

This gets rid of all convertible-related code, including vehicle install/remove blocking on any vehicle with convertible flag, with minimal losses (some things like #28976 are a write off in existing saves)

There was an earlier attempt in #46805 but I don't believe you can do this migration mostly lossless with json alone.

Had to add some code to support 2 things:

1. Add "item_variables" to itype, they are then copied over to instance of item's item_vars when one is created - this is so itypes are able to store variables as "presets", once an item is spawed it gets a copy and is then taking over and using their normal item::get_var/set_var to manipulate them. This allows having a preset of "folding_parts" the generic unfolding can use to produce a vehicle out of that parts list.

2. Add support for reset_item_vars in Item_factory::migrate_item , this allows to reset the folding_parts (or any other) variable to the item prototype value, this allows to migrate the old parts to new and add the corresponding folding_parts so they can unfold.

Stuff changed

1. The folding_bicycle vehicle used light frames (so: not "generically" foldable), and "convertible" tag + iuse action that used convertible tag to spawn a fresh bicycle on activation, this caused a bunch of issues from the flag not persisting through racking on bike rack to repairing demolished tiles on unfolding.

   • The item folding_bicycle is migrated to folded_bicycle - this one will use "generic" folding code paths.
   • In case it's unfolded as a vehicle it should convert parts to match folded_bicycle and lose convertible* flags.
   • In case it's attached to a vehicle it's already a goner unfortunately due to Foldable bike can't be folded after unloaded from bike racks #28976 so it's left alone.

2. wheelchair the vehicle already uses folding parts therefore mostly cosmetic adjustments were done to it.

   • The item folded_wheelchair which used convertible code is migrated to folded_wheelchair_generic which is the generic one.
   • It now has a folded_wheelchair_generic item that can be placed and unfolds into the wheelchair vehicle.
   • Existing wheelchair vehicles are untouched, they should fold into item closely matching folded_wheelchair (sans vehicle name).

3. Inflatable boat is probably weirdest of them all, it also had the same issues but also didn't sink if you destroyed one of the parts (sinking is out of scope of this patch)

   • The item inflatable_boat is migrated to folded_inflatable_boat, to use "generic" folding code, also weight/volume adjusted to match the folded/unfolded versions for Inflatable boat volume and weight change when unused vs folded #48113 and "folded inflatable boat" very different from inflatable boat #51005
   • The vehicle inflatable_boat remains exactly the same
   • inflatable_section and inflatable_airbag (parts the inflatable boat is made of) now have 2 new flags each: NO_INSTALL_PLAYER, NO_UNINSTALL - to match behaviour of vehicles flagged convertible - vehicle ui code did not allow modifications (and unbolting quarter of an inflatable boat makes no sense anyway)

The bad parts

1. The "generic" folding code is saving json string as one of the item's variables, and that causes the prototypes for having an unfoldable item be super ugly since it's escaped json string as seen for example here can't think of a better solution right now that doesn't involve changing more code than necessary.

2. Inflatable boat required a pump before - it was handled in the iuse handler, for now the "generic" folding vehicles have nowhere to put it into and I wanted to keep this already awkward patch relatively light - I cheated a bit by adding pump into the description. Folding/unfolding has to become an activity either way, as current time of 500 moves to un/fold is unreasonable, that's the opportunity to let specific parts (inflatable bags for example) require pumps to unfold, or other tools depending on the parts involved.

3. Any folding bicycle that already passed a bike racking activity "lost" it's convertible flag and can no longer be differentiated from any other bicycle, so I decided to write them off and leave them as non-foldable.

Describe alternatives you've considered

Leaving convertible code to rot more

Testing

Before applying patch prepare map or load the one I prepared:
for each of (folding bicycle, wheelchair, inflatable boat):
spawn two and drop them nearby
spawn one and inflate/unfold it nearby
spawn one + any vehicle with rack and rack it on the vehicle

Save, apply patch and reload that save, check that:

• folding bicycle item should convert to the new one and still unfolds when you activate it
• folding bicycle item 2 should match the weight/volume of the one you unfolded after folding it.
• folding bicycle vehicle should convert to the new one with folding frames
• folding bicycle on vehicle rack is still using light frames and unfoldable if you take it off (due to Foldable bike can't be folded after unloaded from bike racks #28976)
• wheelcart item should unfold into a wheelcart when you activate it
• wheelcart item 2 should match the weight/volume of the one you unfolded after folding it.
• wheelcart the vehicle should have no changes
• wheelcart on vehicle rack should be folding after you take it off
• inflatable boat item should unfold into a boat when you activate it
• inflatable boat 2 should match the weight/volume of the one you unfolded after folding it.
• inflatable boat the vehicle should have no changes
• inflatable boat the vehicle should not allow you to install/remove sections or inflated bags.

Unit test is removed for 3 reasons:

1. It misses basic things like demolishing whole tiles makes them regenerate on fold/unfold cycle (demonstrated in video 1)
2. There is no longer an 'iuse' to actually run the check, or degradation "transfer" that the old code was trying to test for - the degradation is stored as part of the "folded_parts" on the item. Manual check with new code is in video 2. Vehicle part degradation in new foldable code is handled by general item serialization code.
3. The current fold/unfold is subpar, it needs to be migrated to activity to allow interruptions and reasonable un/fold times and requiring tools, which will be a follow up patch.

Additional context

Regenerating parts of a vehicle on fold/unfold cycle (in old convertible code)
https://user-images.githubusercontent.com/6560075/180669156-1164c82e-72c8-4ecd-8400-d362010e0fb1.mp4

"New" folding vehicles keep their damage and degradation on fold/unfold cycle
https://user-images.githubusercontent.com/6560075/180669217-cc95cd99-9959-40e9-96e9-6998e6c3343c.mp4