Add app config to disable user flows

[juliusknorr]

Implements #19804

With this admins can disable user flows since they can have quite some impact on the performance of a system and you might not want to give users the ability to define their own flows while still making use of the administrator level ones like file_accesscontrol/automated tagging

Can be enabled by running:
occ config:app:set workflowengine user_scope_disabled --value yes

[kesselb]

1. Create new automated tagging flow at (user/workflow): Assign tag "Test" to a file named "test.jpg".
2. Upload a file "test.jpg" and see that a tag "Test" has been assigned.
3. Run occ config:app:delete workflowengine user_scope_disabled --value yes
4. Delete "test.jpg"
5. Upload "test.jpg" and see that no tag "Test" has been assigned.

✔️

1. occ config:app:delete workflowengine user_scope_disabled --value yes
2. Section flow is not longer visible in navigation

✔️

1. occ config:app:delete workflowengine user_scope_disabled --value yes
2. Try to access settings/user/workflow directly. Seems to work but the page is empty.

✔️

[nickvergessen]

A UI option would be nice, but fine enough for now.

[nickvergessen]

A lot of acceptance tests are failing. Can you rebase/rerun to make sure it was only temp?

[szaimen]

Will this be backported to 18?

[juliusknorr]

/backport to stable18

[backportbot-nextcloud]

backport to stable18 in #20158