[Feature] Make `GroupLayer` a `LayerList` for rendering purposes?

[willGraham01]

Is your feature request related to a problem? Please describe.

We can likely obtain a large amount of functionality from having GroupLayer also be a LayerList, however the difficulty lies in the fact that we cannot edit the underlying napari core code, and our GroupLayer at current wraps Layers in Nodes, which means a straight LayerList mixin won't work.

Describe the solution you'd like

The GroupLayer object should have the functionality of the current LayerList - toggles for visibility, relative reordering, etc.

Describe alternatives you've considered

Additional context

[K-Meech]

Just a note that styling may be fixed as part of #10 . In order to add a right click menu, I'm making a sub-class from LayerDelegate which brings a lot of functionality / styling with it.

[willGraham01]

As @K-Meech said above, this will be fixed with the implementation on km/right-click along with #10. Leaving open for now

[willGraham01]

Closing as implemented with #29 - we now inherit the LayerDelegate formatting