unify stackable item logic

[scarf005]

Purpose of change

after #3489, there has been numerous issues and fixes with count-by-charges ("the stackable") items:

• fix: account for charges on salvage #3973
• revert: "refactor: use std::clamp" #4007
• fix: prevent full ownership transfer when trading with partial charges of item #4008
• fix: prevent debugmsg while refilling liquid container with another one #4010
• Seatbelts do not drop seat belt item when uninstalled, but range of synthetic fabric #4012
• fix: leashing animal using entire stack of rope #4033
• items have been destacked  #4061

however, they all does not solve the fundemental issue: they work on different APIs.

• singular items use game_object::detach
• count-by-charge items use item::split

https://github.com/cataclysmbnteam/Cataclysm-BN/blob/6bff212696c4832de7168d10e8b7f6db6de09e51/src/activity_actor.cpp#L1179-L1185

For every time an item may be stackable, this logic needs to be duplicated with
item::count_by_charges.

This is problemetic in numerous ways:

• error-prone
• waste of time and effort
• makes code harder to read and maintain

Proposed Change

1. Try to find functions that assume non-stackable items, e.g detach
2. Deprecate them and replace them with functions use assume stackable items, e.g split
3. Convert all non-stackable items into stackables of maximum stack size of 1.
4. chaos ensues
5. Fix remaining issues.

[MarcinSzymanek]

Is this being worked on?