Restrict READ_FRAME_BUFFER to signature only

We want to restrict screen reading permissions
to signature only so only the platform and
apps signed with the platform key can access
the device screen.

Add @removed and @hide to the permission so that it's
not in the docs any more without breaking any existing
apps referring to the permissions.

Bug: 111131054
Test: manually tested screenshot & bugreport
Test: atest PermissionsHostTest
Test: make & verified generated file
out/target/common/obj/PACKAGING/hiddenapi-light-greylist.txt
contains READ_FRAME_BUFFER

Change-Id: I8294aff965e889335a495ab792f893957d39ec5d

Change-Id: I8294aff965e889335a495ab792f893957d39ec5d