Core/Handlers: Fix a crash in HandleCharFactionOrRaceChange

Ensure there's always valid character name data present, even for
characters that were manually inserted into the database, by adding
character name data on char enum if needed.
Core/Handlers: Prevent some cheating in CharacterHandler

Prevents factionchanging and char customising of characters that do not
belong to the current account.
Core/Handlers: Missing returns after KickPlayer() call
Core/Maps: Prevent creating maps without a valid Map.dbc entry

Closes #9181
Merge remote-tracking branch 'tc/master' into mmaps