fix: crafted items no longer try to set default ammotype for items spawned empty

[chaosvolt]

Purpose of change (The Why)

Fixes #4860 by making it so crafting tools won't create a weird situation where the item is empty but counts as having an ammotype assigned under the hood.

Describe the solution (The How)

In crafting.cpp, added a check in the complete_craft where it asks if the item being created has no ammo loaded into it, and if so makes sure to unset the ammotype from it so it won't be in a paradoxical "I'm loaded but empty" situation which is only possible to clear by loading the exact ammo it wants and then unloading it.

Describe alternatives you've considered

I was real tempted to be lazy and just fix any items affected by this stupid bug in JSON by removing use of initial_charges from offending items...

Testing

1. Compiled and load-tested.
2. Gave myself debug hammerspace and all recipes.
3. Crafted an alcohol-fueled soldering item, confirmed I can now load ethanol into it.
4. Crafted a candle, signal flare, gasoline lantern, and medium plutonium battery to be sure that various other types of craft are still created correctly.
5. Itemgroup tested home_hw to confirm that soda can stove kits still spawn fully-loaded in it.

Additional context

Checklist

Mandatory

• I wrote the PR title in conventional commit format.
• I ran the code formatter.
• I linked any relevant issues using github keyword syntax like closes #1234 in Summary of the PR so it can be closed automatically.
• I've committed my changes to new branch that isn't main so it won't cause conflict when updating main branch later.