Feature/storages

At the moment only the autocreated fileadmin storage was supported.

With this request the configured storages are checked, so files outside the fileadmin can be migrated.

The main changes are in `\WE\WeDam2fal62\Domain\Repository\DamfalfileRepository::getStorageForFile` and `\WE\WeDam2fal62\Domain\Repository\DamfalfileRepository::getIdentifier`.