Make files settings admin configurable

[bromiesTM]

Summary

• This gives an admin the ability to override user settings for the file app. For example, to always show hidden files.
• Adds unitests for https://github.com/nextcloud/server/blob/master/apps/files/lib/Service/UserConfig.php
• Fixes a bug where the "Invalid config value" exception is never thrown

To set the config run

ooc config:app:set --value <yes/no> files crop_image_previews
ooc config:app:set --value <yes/no> files show_hidden
ooc config:app:set --value <yes/no> files sort_favorites_first
ooc config:app:set --value <yes/no> files sort_folders_first
ooc config:app:set --value <yes/no> files grid_view
ooc config:app:set --value <yes/no> files folder_tree

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)

[solracsf]

Use Contructor property promotion

[bromiesTM]

Done

[bromiesTM]

🚧 Switched back to draft to make the settings less aggressive