[CR][WIP] Add effect tests

[wapcaplet]

Summary

SUMMARY: Infrastructure "Add tests for effects on creature and player"

Purpose of change

To have some tests on effects, how they work, and how they are applied to creatures / characters / monsters / players.

Describe the solution

Adds new tests (many still in progress or planned):

• effect class and its functions: tests/effect_test.cpp
  • get/set/mod/mult duration, max duration, start time
  • get/set body part
  • intensity, max intensity, get/set/mod intensity
  • permanence/pause/unpause
  • effect modifiers (base_mods and scaling_mods, in progress)
• creature effect functions: tests/creature_effect_test.cpp
  • adding, getting, modifying, removing effects
  • duration, body part, intensity of effects
  • immunity and resistance to effects
• player effect functions (hardcoded effects): tests/player_effect_tests.cpp
  • bite antibiotic effects (working well, covers something that could be JSONized one day)
  • bite recovery (slow to execute, inaccurate, flaky)
  • mending, disabled (lengthy and don't have much to say)
  • lying down but cannot sleep

Describe alternatives you've considered

Tests without effects

Testing

tests/cata_test [effect]

Additional context

Work in progress. This is becoming much more in-depth and sizable than I originally planned, so I may break off the player hardcoded effect tests (the least complete, and least reliable of the bunch) into a separate PR.

Comments and suggestions are welcome; I am learning the effects system and documenting it as I go, and would prefer to avoid adding false or misleading information.

[wapcaplet]

This is too large for one PR to contain now. Closing.

New PRs:
Part 1: #40222
Part 2: #40234
Part 3: #40270