Migrate screenshot methods to AIDL

Additonal service, named as "SurfaceFlingerAIDL", is added to surfaceflinger during the process of migrating ISurfaceComposer interface to AIDL. New changes are put into namespace, android::gui. Once migration is complete, this service will be deleted.

This CL migrates Screenshot methods to AIDL, more will come.

Bug: 211037638
Test: screencap
Merged-In: Idee91fa2444646639735847b1c76e983af39227f
Change-Id: Idee91fa2444646639735847b1c76e983af39227f
21 files changed