Magicylsm: NPCs can now teach spells

[ghost]

Summary

SUMMARY: Features "Magicylsm: NPCs can now teach spells"

Purpose of change

Magicylsm: NPCs can now teach spells

Describe the solution

Added a json field for NPC classes, that list spells and levels, like player professions do.
THe NPC then has them added to their "spellbook" when they are spawned.
The NPC spells ar ethen added to the list of things that can be taught in dialogue.
This starts the usual training activity, but with learning a spell at the end of it.

Also fixed a bug in the process that I dont think has been reported, where you can start training with one NPC, then resume it with a different one.

NPCs cant cast spells yet, thats coming, this just lets them know and teach spells.

Describe alternatives you've considered

N/A

Testing

Tested saving/loading with NPC spells, added a debug menu option to print to console what spells each NPC knows.
Tested interrupting and resuming training activity.
Tested time taken for spells to be learned via training
tested spells that are known by the player and spells that arenot.
tested declining to be locked out of wizard type class when training finishes.

Additional context

N/A

[KorGgenT]

A couple things: A lot more of these temporary variables can be const, because quite a few of the functions you're using in spell are const.

In addition, if all you need is the name or other values from the spell_type you can simply do spell_id->name.translated() or similar, instead of getting the spell object.

Also, there are a couple of autos hanging around

[KorGgenT]

looks like the cost isn't getting calculated correctly.

[ghost]

looks like the cost isn't getting calculated correctly.

The cost is 0 when its a follower teaching you.

[ghost]

Merge conflict caused some weirdness , will fix.