Expose filesystem read events in filesystem perms.

Without this, we only have visibility into writes.

Looking at traces, we realised for many of the files we care about (.dex, .apk)
most filesystem events are actually reads.

See aosp/661781 for matching SELinux change.

Bug: 73625480

Change-Id: Ic4dbf4f0505a12de8b1ed133499813b6466c3cbe