chore: Remove nextcloud package

[provokateurin]

Moved to https://github.com/provokateurin/nextcloud.dart

[provokateurin]

Some of the contributing guidelines need to be removed here and added to the other repo.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!

[Leptopoda]

please also make a release in the new repo so we can import the package through a tag.
Similar to #3195 the nextcloud package should import its sub packages through the created tag with an override to the local path.

This would allow us to also import the testing libraries in here (even though this is not something we like to do).
See: https://github.com/dart-lang/http/blob/ba5f36800879af15f0531a0c5723e9baef7a0a57/pkgs/http_client_conformance_tests/pubspec.yaml#L14-L20

[provokateurin]

I don't really see a benefit, but if you want to change it we can do it later. For now this isn't important.

[Leptopoda]

Then we should at least create an issue.
Let me know when I should do the final review (i.e. you changed the last remaining stuff like the contributing guidelines)

[provokateurin]

provokateurin/nextcloud.dart@6c7b245

[provokateurin]

Also updated the .gitmodules

[provokateurin]

We can't actually remove the git submodules, because they are also used to generate assets.

[Leptopoda]

Does it make sense to move the asset generation to a separate package in the nextcloud.dart repo?
I'm thinking about nextcloud_assets.

But I agree that this might be a longshot goal.

[provokateurin]

That doesn't help here. I will add back the ones that are still used for asset generation, the others can be removed.