[Feature]: Collapsable expansion categories

[luismigil]

Describe the feature

Hi all! I think that its a good idea to add collapsable sections by expansion

Describe the implementation

BetterBags will show a header section with the name of the expansion and inside tha categories for each expansion, let me know if you think that its a good idea :)

[zeptognome]

agree that this could be a great feature, but duplicate of #73 I think

[Cidan]

Duplicate of #73