Migrate overmap specials

[dseguin]

Summary

None

Purpose of change

Fixes #53224.
Fixes #53423.
Fixes #51856.

Describe the solution

I've added a new type "overmap_special_migration" to handle overmap specials that have been migrated or removed:

{
  "type": "overmap_special_migration",
  "id": "Military Bunker",
  "new_id": "military_bunker"
},
{
  "type": "overmap_special_migration",
  "id": "basin",
  "//": "Removed - no new id"
}

TODO:

• Handle known moved/removed specials (temporary measure)
• Handle FakeSpecial_ buildings from overmap_specials::create_building_from It turns out it didn't require anything special at all, just non-fake id definitions
• Jsonify migration so that content creators can migrate specials themselves

Describe alternatives you've considered

I could leave it at hardcoded exceptions, which would work but not optimal.

Testing

Tested loading saves from the linked issues.

Additional context

[wapcaplet]

Tested OK with my save games (see linked issues). Glad to see these bugs finally resolved!

[dseguin]

There's an issue with one two of the mods using an old id (s_jewelry instead of s_jewelry_shop). One of the tests failed because the consistency check caught it. At least the check is working as intended!