Option to start a game with mixed difficulty

[RasmusAntons]

I would like to be able to start a game with goals from different difficulties. This would especially be useful for the lockout mode, where teams can race for the easy goals first.

This could either be fixed (e.g. 5 x easy, 10 x medium, 10 x hard) or something like the tag system (max 8 easy, max 15 medium, max 15 hard).

I guess this is already possible to emulate with tags in a custom datapack but then we'd have to override all goals and put them in the same difficulty, so it would be nicer to have that option directly.