Improve heal location reading/writing

[GriffinRichards]

This contains commits from #447. This was to avoid conflicts, but now that has conflicts too so here we are. Ideally this would be opened after it's merged, but I'm away through Monday so I'm making it available now on the off chance yall want to do the release this weekend.

To see the diff of just the new changes: https://github.com/GriffinRichards/porymap/compare/95838ac..cfdcb4d

Changes:

• SPAWN_* or HEAL_LOCATION_* constants in include/constants/heal_locations.h will not be deleted if they aren't used in src/data/heal_locations.h. This is to support https://github.com/pret/pokeemerald/pull/1671
• SPAWN_* and HEAL_LOCATION_* may now be used interchangeably, and are not strictly enforced based on the config settings.
• Heal location table data may now be ordered arbitrarily, independent of the other data tables and their constant values.
• If heal location data is present in at least 1 but not all of the heal location tables, entries with default values will be added for the rest.
• Fixed a bug where heal locations created via New Map could temporarily have an incorrect name for their respawn map.