Effect Idea: Set Gamemode

[MoSadie]

Would have the same checks as the F3+F4 screen, I'll write a better description later.

[MoSadie]

LOL it turns out that Minecraft literally just sends a hardcoded gamemode command for that menu.

Only needed to add the handler in core, will be in v2.2.0.

[MoSadie]

TODO before closure:

• [X] Implement effect in code
• [x] Write Wiki page
• [x] Create Stream Deck Icon