Abstract screenshot actions into ActionExecutor

The actions need to do things involving the window/dismissal. It
doesn't make sense to give the action provider direct access to these
references; instead pull it into an ActionExecutor that can e.g. start
shared transitions and send pending intents.

Bug: 329659738
Test: atest DefaultScreenshotActionsProviderTest
Flag: ACONFIG com.android.systemui.screenshot_shelf_ui DEVELOPMENT
Change-Id: I7f5a9fa95a9106c76fcbacdb94db4a7568f56490