Modify DisplayList and LayerStateStack naming conventions to match Flutter style guidelines #114089
Description
As pointed out in flutter/engine#36458, parts of the DL source code have been following a mix of Skia and Flutter style guidelines and as we move more towards hiding or eliminating the Skia APIs behind or in favor of DL APIs, we should be adhering more closely to the Flutter style.
The PR was for the new LayerStateStack mechanism that will be central to our migration to DL APIs throughout the layer code, so both mechanisms should be recast with fresh API names.