Deduplicate item contents description in the examine display

[moxian]

Summary

Interface "Deduplicate item contents description in the examine display"

Purpose of change

If we have several identical items in our pockets, each individual item is listed separately in the examine display.
This is unwieldly. See:

Describe the solution

Merge the individual items if they are identical into a single one. This is already how it works for pocket contents, I'm doing the same thing to the item contents now.

Describe alternatives you've considered

N/A

Testing

Additional context

This still looks a bit silly with liquid contents (the liquid's description is duplicated), but at least that's not a regression.

[db48x]

There's very little performance cost to following that pointer, so feel free to combine the code to improve maintainability.

[moxian]

clang-tidy complains about my code, but from a different pr. I'll pr a fix, separately.
Test failures are unrelated.
(at least this was the case before i drafted -> undrafted this. I didn't realize that would kick the checks again)