Asset browser - shape key actions as valid pose (object) actions

All functionality (Apply/Blend pose etc.) that currently is for pose assets in asset library does not currently work for shapekey actions (Blender 5.1.2).

Then again also integrating shapekey actions directly into action editor instead of separate shapekey editor is a point as well. (Workaround as of now is to put shapekey action slot into f.ex. another action to expose shapekeys as sliders there.)