[ENH] Rename "Selected items" to "groups"

[Vogliadicone]

Just a tiny issue: Sometimes you speak of groups and other times you use "Selected items" when referring to the same groups:

For consistency I would suggest to change these two "Selected items" to "groups".

• Token Action HUD Core: 1.4.13
• Token Action HUD SWADE: 0.7.5
• Foundry VTT: 11.305
• Browser: Google Chrome

[Larkinabout]

It's because items can be either groups or actions. Items is more referring to the items within the list than it is any specific part of the HUD. I'll have a think about how to better clarify it.

[Larkinabout]

Leaving as items as they are distinct from just groups.