Make socket group sort order persistent

[Lothrik]

Prior to this PR doing basically anything to manipulate the order of your socket groups (deleting them, reordering them, etc) would cause your active socket group selection in both the skills tab and calcs tab to change.

This is not desirable behavior — users expect their active socket group to remain the same regardless of what they do (unless they delete the active socket group of course, and even then it should come back if they undo that).

This PR implements support for all of that, hopefully in a bug-free manner.

Video Demo: https://www.youtube.com/watch?v=EcbuMPWKr3Q

Example PoB: https://pobb.in/JxITTra78keh

[QuickStick123]

This is a big improvement though and the current changes seem fairly robust apart from these couple cases.
Changing the active gem here doesn't create undo states

Changing between skill sets can change which gem is active. Also changing one skill set will effect the other.

->

->