Move town names settings to "New world" window

[Wuzzy]

Currently, you must go into the game settings to change the town name generator.

However, I think it makes more sense to move this setting into the "New world" window, since this setting is only relevant on world creation, and has no relevance at all in any other situation. It cannot be changed after a world was created. Therefore, this setting is actually part of the world generator, so it makes sense to have it in that window.

[2TallTyler]

There’s an open PR to do exactly this.
https://github.com/OpenTTD/OpenTTD/pull/8566