Allow moving the datadirectory to another location

⚠️ This issue respects the following points: ⚠️ • This is a bug, not a question or a configuration/webserver/proxy issue. • This issue is not already reported on [Github]( OR [Nextcloud Community Forum]( _(I've searched it)_. • Nextcloud Server is up to date. See [Maintenance and Release Schedule]( for supported versions. • I agree to follow Nextcloud's [Code of Conduct]( Bug description The datadirectory is set up when installing a nextcloud instance. While changing it in the config.php is possible (see this is not supported and leads to side effects, e.g. missing shares from group folders. CC: @sorbaugh Steps to reproduce Move the datadirectory to a different location after initial installation is done. Expected behavior Either it should work out of the box, the change should be automatically detected or there should be a supported way (e.g. via occ) to change the datadirectory. Installation method None Nextclo…