Move display-related string colorization functions out of Character class

[wapcaplet]

Summary

None

Purpose of change

To de-bloat the Character class and make display-related functions more logically named.

Describe the solution

Move and rename these functions out of the Character class, into a display namespace in panels.h|cpp:

• Character::get_thirst_description -> display::thirst_text_color
• Character::get_hunger_description -> display::hunger_text_color
• Character::get_fatigue_description -> display::fatigue_text_color
• Character::get_pain_description -> display::pain_text_color
• Character::get_weight_description -> display::weight_text_color
• Character::get_weight_string -> display::weight_string
• Character::get_weight_long_description -> display::weight_long_description
• static weariness_description -> display::weariness_text_color

The new text_color names were chosen to reflect the fact that these functions return a (string, color) or (translation, color) pair.

Leave the existing activity_level_str function in place in the new namespace (formerly called activity_level).

Describe alternatives you've considered

Going the other way around (migrating display functions from panels into character) seemed like the wrong choice, considering the massive size of the Character class already. These functions are only loosely coupled to the class and don't really belong here.

Considering the sort of general-purpose usage of these functions throughout the codebase (not just for the panels), perhaps panels.h|cpp is not ideal either; however the panels are the biggest consumer of these functions (and the incoming panel widgets in #50945 do too), plus there is a collection of similar functions already in there (dex_string, focus_color, get_moon and so forth), so I think it's a good fit.

Testing

Play the game and ensure the colored descriptive text in sidebar still looks OK.

Additional context

This is mainly in support of #50945

Probably easiest to review commit-by-commit (one or two functions factored out per commit).

[actual-nh]

I am tempted to call reductions in the size of character.cpp a bugfix... EDIT: Sorry, didn't realize you were editing the labels at the same time as I was.

[wapcaplet]

Failing test case in "Basic Build / Basic Build and Test (GCC 9, Curses, LTO)" appears unrelated:

(~[slow] ~[.])=> ../tests/field_test.cpp:215: FAILED:
(~[slow] ~[.])=>   CHECK( fields_test_turns() < time_limit_turns )
(~[slow] ~[.])=> with expansion:
Error: (~[slow] ~[.])=>   1800 (0x708) < 1800 (0x708)
(~[slow] ~[.])=> with message:
(~[slow] ~[.])=>   Fire should've spread to the far point in under 1800 turns

[wapcaplet]

Something got screwed up in rebasing after resolving conflicts with master. I will investigate later today - putting back in Draft for the moment.

Never mind, looks like I somehow had some stale .o files. Compiles OK now, and all tests pass locally, except a couple in vehicle_part_test.cpp and vehicle_power_test.cpp that appear to be unrelated, and have been raised in the CDDA Discord development channel recently as well (see #51082).