Add file access concessions for SYSTEM_GALLERY

Apps that have MODE_ALLOWED for OP_WRITE_MEDIA_IMAGES can bypass
MediaProvider restrictions when accessing an image file through FUSE.
This means that those apps can:
    * Create images wherever they want
    * Open all images for read and write
    * Delete all images
    * Rename all images
    * Access location metadata on all images
'All images', of course, includes images owned by other apps.

Similarly, apps with OP_WRITE_MEDIA_VIDEO can do the same for video
files.

Since SYSTEM_GALLERY has both of those app-ops by default, this CL gives
them full access to image and video files.

Test: atest FuseDaemonHostTest
Bug: 146777893

Change-Id: If12d6e511791f936abf883523fc794b7ef1c6c72
5 files changed