Creates a new permission for /cache/recovery

This permission was created mostly for dumpstate (so it can include
recovery files on bugreports when an OTA fails), but it was applied to
uncrypt and recovery as well (since it had a wider access before).

Grant access to cache_recovery_file where we previously granted access
to cache_file. Add auditallow rules to determine if this is really
needed.

BUG: 25351711
Change-Id: I07745181dbb4f0bde75694ea31b3ab79a4682f18