Fix Sonarr media management settings and improve root folder handling

[Callum027]

This fixes a number of bugs with loading and setting media management configuration in Sonarr.

Add a new delete_unmanaged_root_folders configuration attribute to the media management block, to enable automatic deletion of root folders not explicitly defined in Buildarr.

• Constrain minimum_free_space to the minimum allowed value of 100 MB, as enforced by Sonarr
• Set chown_group to be of type Optional[str] to allow empty strings to be defined (handled the same as None)
• Change root_folders to be of type Set[NonEmptyStr] to ensure only unique values are handled internally
• Add the delete_unmanaged_root_folders attribute for allowing automatic deletion of root folders in Sonarr not defined in Buildarr
• Add the missing unmonitor_deleted_episodes to the remote map entries, causing it to not be read from Sonarr or updated when defined in Buildarr
• Fix the root folder tree printed in logging messages to contain root_folders