Update to MUI2 RC3

[ghzdude]

What

Updates MUI2 to RC3.

Implementation Details

remove casts to PanelSyncHandler
fix list widget construction
delete cached panel for entry selector
delete mui2 mixins as they are no longer needed

Outcome

we can finally release™ maybe

[ALongStringOfNumbers]

Needs to up the minimum MUI2 dep in the mod annotation in GregtechMod.java

[ALongStringOfNumbers]

Should probably stop adding the MUI2 mixin config to the list of configs in the late mixin loader, since it is empty. Can just comment it out, incase we need to add more mixins at a later time.

The Description for the channels in the Ender Fluid Link cover has a formatting error, at least that is what it says in game. If you click on the settings to set the description, the error will be in the title.

Also a formatting error in the input buses when hovering over the programmeed circuit selector slot.

Some weirdness going on with the syncing in fluid hatches. I added a bucket of water to the hatch, which updated the display text. I then removed the water, but the fluid name stayed in the display text, and the fluid texture stayed in the fluid slot. (This was not attached to a multiblock at the time)

[ALongStringOfNumbers]

Programmed circuit slot is still messed up in the input buses, as the newlines are not getting recognized.