2022-June-12 - Prerelease - 2.6.895

Rename MoveDescription fields to be clear what they're for. (#10631)

Also update variables and function names in related code to be explicit as well (e.g. being clear about matchers that check for sea transports and not any other kind).

Note: I don't believe anything changing here is part of the serialized game state. For example, UndoableMove doesn't use MoveDescription.