Rename Surface callback events to state

Surface Callback events were essentially communicating the state of the
surface. Rename the callback and the API to "state" instead of "event".

Bug: 217627954
Test: atest CtsPhotoPickerTest
Change-Id: Ic666f952248a9ca96b4160d38cb71f97240b3ac5
Merged-In: Ic666f952248a9ca96b4160d38cb71f97240b3ac5
6 files changed