[DDA Port] Map reference migration part 1

[olanti-p]

Summary

SUMMARY: Infrastructure "[DDA Port] Port code to use global getters instead of g->u and g->m"

Purpose of change

Reducing dependency on game.h and game class.

Describe the solution

This and following PRs are cherry-picks of corresponding DDA PRs.
This one is CleverRaven/Cataclysm-DDA#41358
The idea is to use get_map(), get_avatar() and get_player_character() instead of including game.h just for g->m or g->u.
Cherry-picks are done somewhat loosely (parts of commits are dropped, parts are adapted for BN) since the divergence is quite noticeable at this point, so some usages of g->u or g->m may remain in the changed files.

Describe alternatives you've considered

Doing this manually, but that would produce even more merge conflicts down the line.

Testing

Compiles locally. No behavior changes intended.

Additional context

These are bound to cause merge conflicts with other open PRs, so in case they're interfering I'm fine with these being put off in favor of other changes.