Add support for Thunderstore plugin

[ZashIn]

Minimal changes to support the Thunderstore Installer plugin (backwards compatible):

• Add a ignore option to BasicModDataChecker: since the argument priority is sadly fixed now, it is added with top priority over the other options.
• For games Valheim and Subnautica (BZ):
  • Ignore *.mohidden.
  • Add Thunderstore community names as BasicGame.GameThunderstoreName attributes.

Alternatively to the BasicGame attribute would be a plugin setting thunderstore_community, see Add game support