Apply diffs to screenshot action updates

Adds a button ID so that updates can be differentiated from
adds/removes.

System assumes that IDs are unique and that actions do not swap order
(would have to be an remove/add with a novel ID).

Bug: 329659738
Test: manual test with logging
Flag: ACONFIG com.android.systemui.screenshot_shelf_ui DEVELOPMENT
Change-Id: I5753511ad7c3ebbe189948ffc10cf2c02ef5b688
Merged-In: I5753511ad7c3ebbe189948ffc10cf2c02ef5b688