Enable Celery Background Manager for additional Backends

[datenzauberai]

This is an implementation to fix #3729 and #3116.

Contributor Checklist

• I have broken down my PR scope into the following TODO tasks
  • Error early on when the configured backend is not a BaseKeyValueStoreBackend
  • Use proper byte-like objects as keys for BaseKeyValueStoreBackend
  • Harden implementation to support celery filesystem backend
  • Enhance implementation to support arbitrary backends via get_result and store_result
• I have run the tests locally and they passed. (refer to testing section in contributing)
• I have added tests, or extended existing tests, to cover any new features or bugs fixed in this PR

optionals

• I have added entry in the CHANGELOG.md
• If this PR needs a follow-up in dash docs, community thread, I have mentioned the relevant URLS as follows
  • this GitHub #PR number updates the dash docs
  • here is the show and tell thread in Plotly Dash community

[camdecoster]

Thanks for creating this PR! Is it in a state where we can review it?

[datenzauberai]

Thanks for creating this PR! Is it in a state where we can review it?

I'm on it, but this still needs work! The manager itself works locally, but I want to have good tests first so that this can be maintained in the future.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
2.4% Duplication on New Code

See analysis details on SonarQube Cloud

[datenzauberai]

@T4rk1n Maybe you could have a quick look. This should work now with the filesystem backend in Celery.

Enabling the other backends would need a more substantial rework, because we would need to use get_result/store_result instead of get/set/delete/expire in BaseKeyValueStoreBackend.

I wonder if it's really worth the effort to rework this, because I guess that many simple cases can now be handled using WebSocket Callbacks. What do you think?