Ensure we have valid permissions when checking whether a move is allowed

[TheOneRing]

If we perform a move and revert we can hit an assert that instantly kills the client.

How to reproduce with 2.8:
#8033 (comment)

In 2.9 we require new database entries to have valid permissions set and fetch the permissions if required.
https://github.com/owncloud/client/pull/8067/files etc

That means that with 2.9 it is basically not possible to run in that scenario.
But if we upgrade from a compromised 2.8 database this can still happen.

TODO:
Fetch the permissions if they are null
https://github.com/owncloud/client/blob/master/src/libsync/discovery.cpp#L1265
https://github.com/owncloud/client/blob/master/src/libsync/discovery.cpp#L1179

[TheOneRing]

If the local permissions are not correct we perform a prohibited move
The move fails with 403 and creates a blacklist entry, but we might get the correct permissions for that file.

In the next sync the we don't retry the move as we have the correct permissions now so we want to restore the original file.
The original file however is now on the blacklist we mark the restoration as ignore and end up in findAndCancelDeletedJob