Feature: Extend Hangfire Plugin with JobManager, Queue Support, and EF Health Check Integration

[lukas-kd]

This PR enhances the Hangfire plugin by introducing a JobManager to orchestrate the various Hangfire job clients (BackgroundJobClient, RecurringJobManager, JobStorage) into a single, unified manager.

Key Changes:

JobManager: Centralized manager for handling Hangfire job clients.
Attribute Configuration: Replaced the JobRegister and moved Timeout and TimeZone configurations to attribute-based setup for more flexible job management.
Queue Support: Added support for specifying job queues, allowing better control over job execution order and prioritization.

Other improvements:

Entity Framework Health Check: Integrated automatic health check registration for Entity Framework, enhancing monitoring and resilience.
WebHost Configurators: Allows to implement configurators for plugins to allow more custom configuration.

[github-actions]

Test Results

 18 files  ±0   18 suites  ±0   26s ⏱️ -1s
360 tests ±0  353 ✅ ±0  7 💤 ±0  0 ❌ ±0 
361 runs  ±0  354 ✅ ±0  7 💤 ±0  0 ❌ ±0 

Results for commit a9d7708. ± Comparison against base commit 6e51c26.

♻️ This comment has been updated with latest results.

[tst-sia]

Still need to validate and test the hangfire changes. Initial impression so far is looking good.

[lukas-kd]

i've also adjusted the test method "GetInaccessibleValue" to be able to look for properties/fields on base type.
So we could easier test handlers on HttpClients and so on.

[tst-sia]

@lukas-kd We'll still need a couple days before we can test the changes as we're short on resources right now and priority doesn't open up much space. I'm certain there won't be that many comments or necessary alterations though.
I hope that's fine with you.

In general we can talk about your expectations in regards to PR reviews so we can find a good middleground between testing on our side and not slowing you down/blocking any of your features.