chore(api): upgrade to api-platform 3.0

[usu]

Superseded #2984 (had to create a new PR, because test workflows didn't run on the old one anymore)

ToDo

• check performance timings (sanity check before/after)
• refactor/fix tests for state processors
• fix phpstan/psalm warning
• review deprecation warnings
• check if in frontend everything is still working
• IRIs of contentNodes not yet consistent (needs the following api-platform fix: fix(normalizer): normalize items in related collection with concrete class api-platform/core#5261)

Stuff for separate PRs

• Review changes done in https://github.com/api-platform/api-platform and take over what makes sense
• Review if we want to support multiple ApiResources in our various extensions (UriTemplateFactory, etc.)
• Register upstream issues
• Plural naming for /reset_password endpoint
• Test coverage for data providers

[usu]

@ecampcore I think this would be ready for another check-up from you guys. Major comments should all be implemented. Last pending point is sanity check on performance. On my local machine I got inconsistent result in both directions. Want to check on the deployment directly, but not really working at the moment. Will try again later.

[BacLuc]

Looks good to me.
Just found the one commented test which was moved, so you could delete it now.

Looked at the coverage, and its still here.
(Don't know where the -0.3 percent are lost).

Could not go through anything very thorough, but i think with another approve it will be good enough.

Thank you very much @usu

[carlobeltrame]

Thanks a lot!

[manuelmeister]

🥳