Allow to pass a var to a TabGroup to save the currently selected tab into #64
Description
This is meant to be used in cases where you want to have 2 mutually exclusive setups, like "Track Bone" and "Track Player Data" or smth, where the tab group index can indicate which mode you are in
[TabGroup("Track Bone", "trackingType")]
// ...
[TabGroup("Track Player Data", trackingType")]
// ...