Remove raw string item constructor

[Procyonae]

Summary

None

Purpose of change

Found a todo that seemed simple enough to give me a break from getting very confused by diagonal rail intersection sprite rotations

Describe the solution

Mainly just changes the old raw string constructor usage with itype_id's statically defined at the top in the standard way
Changes a couple of knock on functions/fields using raw strings when they shouldn't be
Changes npc_talks receive_item bc it was passing a itype_id and then conditionally reparsing it as an item_group_id which seemed really hacky

Describe alternatives you've considered

Same wants doing for a few other types notably monsters
I'm not a fan of harvest_entry::drop which is a raw string which can be treated as a itype_id or item_group_id depending on the associated json harvest_drop_type's "group" field but that didn't seem super simple to change

Testing

Game and tests compile, will do a full review once the tests have ran... or Guardian could just yolo it '^^

Additional context

This was a 20 minute adventure until I got to /tests .-.

[GuardianDll]

Do we want to enforce it somehow, to prevent it from occuring in future?
Also please resolve branch conflicts

[Procyonae]

Do we want to enforce it somehow, to prevent it from occuring in future?

I removed the constructor overload (the first commit) so unless someone tried to add one back that's not an issue