Some vite nitpicks

[JulianKniephoff]

This does several things:

• It swaps out @vitejs/plugin-react for the -swc variant to speed up the build even further.
• Remove a deprecation warning. (I thought my job was done with Fix build warnings #430 but alas ... 🥲)
• Clean up some other small things that were overlooked in Replace react-script with vite #471.

See individual commits and their messages for more details.

[github-actions]

This pull request is deployed at test.admin-interface.opencast.org/515/2024-06-03_17-59-00/ .
It might take a few minutes for it to become available.

[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-515

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-515

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.

[ziegenberg]

It still builds, it runs and the changes make sense. (I had a branch with the same fixes on my machine)