Improve the selection of "list" fields like tags or features in "Select metadata to import" window

[HerrKnarz]

Feature description

Since some metadata addons like MobyGames or Giant Bomb add a mass amount of tags and sometimes features to a game, it would be great if it was possible to check all boxes for those fields in the "Select metadata to import" window at once. That new function should leave the ones on the other side unaffected. That would make it easier to merge tags from several metadata sources for example. I guess a good and easy implementation would be a context menu for each of those fields with the options to "select all", "select none", "toggle selected".

Screenshots

No response