refactor: Port away from OC.SystemTags

[CarlSchwan]

According to github search this was the only remaining usage left outside of server: https://github.com/search?q=org%3Anextcloud%20OC.SystemTags&type=code

[nickvergessen]

So we add many dependencies and each app has to load it's own list of tags going forward? Kind of sad.

[susnux]

So we add many dependencies

There is only one runtime dependency added the rest is just dev time.

and each app has to load it's own list of tags going forward?

We could provide some alternative but this is the only app that makes use of it, so not sure if it makes sense?

[nickvergessen]

/backport to stable32