[Mount ISO Action] Optimize getDeviceFromBackingFile
Only query for
StorageAccess as only this device type can be mounted,
safes around 2/3 of needlessly created
Devices significantly speeding
up the lookup.
property() instead of
allProperties(), the latter of which
does an explicit
GetAll DBus query. Effectively, will probably not do
much because it will be the first time the
Device properties are
queried but it's still slightly convoluted.
Right-clicking ISO files is still slow but a lot less so.
Mounting and unmounting (and determining whether it's mounted) an ISO file still works.