Condense item stacks with charges only when they are mergeable

[ferociousdork]

Summary

Bugfixes "Smoking rack condensing disparate items into one stack"

Purpose of change

Fixes #40007
Fixes #48384

Smoking racks condense the charges of the items inserted based just on item type, ignoring other significant differences (normal meat vs. mutant meat in #40007, calorie counts in #48384). Another one would be relative rot, currently the smoking rack can turn stacks of old meat into fresh ones and vice versa.

The exact same problem exists for mills, which is also fixed by this PR.

Describe the solution

This PR uses item::merge_charges to determine if charges should be merged or not. This causes disparate components to be tracked separately. Next to that, it uses display_name when examining smoking racks / mills so the differences can be inspected visually.

While testing I found that comestibles with the cooks_like field ignore relative rot, i.e. they are always created completely fresh. Since it is somewhat related (it can still turn old food into fresh), and the fix is just two lines, I've added that as well.

Describe alternatives you've considered

This change affects component tracking in all items that use charges, not just smoking rack and mill contents. Therefore I considered doing this just for comestibles to reduce the chance of bugs. However, distinguishing components the same way the inventory does could be useful everywhere.

Testing

Tested item stacking in smoking racks / mills, tested components of crafting results. See screenshots below.

Additional context

Smoker contents separating by type of meat:

Mill contents separating by freshness:

Messages upon inserting food:

Old and fresh components being tracked separately:

[actual-nh]

Do make sure this doesn't make the "can't mix liquids from two sources" problem worse - as in adding it to more things. (Things with different nutrition should be mergeable, just with the result as a weighted average of the inputs' nutrition values.)

[ferociousdork]

It doesn't make it worse, but it does nothing to make it better either. If two stacks are currently being separated in the inventory, they are now also separated in the smoking rack / mill.