WaitFor integration with Health Check Service

[mitchdenny]

Description

This PR integrates WaitFor with health checks from the .NET hosting model. Extension methods like AddRedis(...) register a health check in DI which uses the connection string which is produced when the resource is provisioned.

A new annotation HealthCheckAnnotation keeps track of the health check names associated with each resource and a health check publisher implementation ResourceNotificationHealthCheckPublisher transcribes health check status from the health check report to a new property on the ResourceEvent (HealthStatus).

In WaitFor we determine whether a resources's dependencies has a HealthCheckAnnotation and if it does it waits for the health status to return healthy.

This PR also introduces a new event .... ConnectionStringAvailableEvent which is used by AddRedis(...) and AddPostgres(...) to detect when the connection string is available so we can store it in a captured string which is used by the health check. This is significant because it allows Azure hosted resources to participate in the health-check enabled WaitFor(...) experience.

In the case of DCP hosted resource sthe ConnectionStringAvailableEvent is fired at the same time as BeforeResourceStartedEvent - but in the case of the AzureProvisioner it is fired after the resource is online in Azure (so the order is roughly opposite) - hence why we needed another event (Azure hosted resources don't get endpoint allocated events).

Checklist

• Is this feature complete?
  • Yes. Ready to ship.
  • No. Follow-up changes expected.
• Are you including unit tests for the changes and scenario tests if relevant?
  • Yes
  • No
• Did you add public API?
  • Yes
    • If yes, did you have an API Review for it?
      • Yes
      • No
    • Did you add <remarks /> and <code /> elements on your triple slash comments?
      • Yes
      • No
  • No
• Does the change make any security assumptions or guarantees?
  • Yes
    • If yes, have you done a threat model and had a security review?
      • Yes
      • No
  • No
• Does the change require an update in our Aspire docs?
  • Yes
    • Link to aspire-docs issue:
  • No

Microsoft Reviewers: Open in CodeFlow

[davidfowl]

This needs tests

[mitchdenny]

This needs tests

Yes it does! I didn't think you'd like me #YOLO merge this one.

[mitchdenny]

/azp run

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