make cancel buttons work for users/groups/access

[ppettit]

Fixes #1182

Just makes the cancel button close the modal which is the behaviour of the old admin UI

[github-actions]

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[github-actions]

Use docker or podman to test this pull request locally.

Run test server using develop.opencast.org as backend:

podman run --rm -it -p 127.0.0.1:3000:3000 ghcr.io/opencast/opencast-admin-interface:pr-1277

Specify a different backend like stable.opencast.org:

podman run --rm -it -p 127.0.0.1:3000:3000 -e PROXY_TARGET=https://stable.opencast.org ghcr.io/opencast/opencast-admin-interface:pr-1277

It may take a few seconds for the interface to spin up.
It will then be available at http://127.0.0.1:3000.
For more options you can pass on to the proxy, take a look at the README.md.

[github-actions]

This pull request is deployed at test.admin-interface.opencast.org/1277/2025-05-14_12-02-36/ .
It might take a few minutes for it to become available.

[Arnei]

Supercedes #1204 I suppose?

[Arnei]

Works and makes sense to me. Small suggestion below

[ppettit]

Supercedes #1204 I suppose?

yes, sorry that was not linked to the issue so i didn't find it. seems like a lot of unrelated changes in that PR too