Allow start command to force waiting resources to start

[JamesNK]

Description

Addresses #5879

This PR makes it possible to force waiting resources to start. The important thing to consider here is waiting resources are already trying to start and they're waiting on BeforeResourceStartedEvent to finish.

I'm not happy about thread safety here. Suggestions welcome.

TODO:

• Functional tests

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
    • Is this introducing a breaking change?
      • Yes
        • Link to aspire-docs issue (please use this breaking-change template):
      • No
        • Link to aspire-docs issue (please use this doc-idea template):
  • No

[Copilot]

Copilot reviewed 5 out of 6 changed files in this pull request and generated no comments.

Files not reviewed (1)

• playground/Stress/Stress.AppHost/Program.cs: Evaluated as low risk

Comments suppressed due to low confidence (3)

src/Aspire.Hosting/Orchestrator/ApplicationOrchestrator.cs:214

• The new behavior introduced by the changes, especially the handling of waiting resources, is not covered by tests. Functional tests need to be added to ensure the correctness of the new logic.

public async Task StartResourceAsync(string resourceName, CancellationToken cancellationToken)

src/Aspire.Hosting/Dcp/DcpExecutor.cs:1620

• [nitpick] The variable name 'appResource' is ambiguous. It should be renamed to 'resourceReference' to match the method parameter.

var appResource = (AppResource)resourceReference;

src/Aspire.Hosting/Dcp/DcpExecutor.cs:1634

• The use of ConcurrentDictionary for _startingResourceState should be reviewed for thread safety, particularly around the WaitForDependenciesTask and WaitCancellation properties.

throw new InvalidOperationException($"Unexpected resource type: {appResource.DcpResource.GetType().FullName}");