Only add double-dash to args if there are previous app-host-added args

[adamint]

Description

It doesn't appear that a double-dash is required to be prepended to application launch args when there are no app host arguments. @mitchdenny does this make sense?

Fixes #7751

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 reviewed 1 out of 1 changed files in this pull request and generated no comments.

[mitchdenny]

Correct. They should be unncessary.

[mitchdenny]

Why not just do the check internally to the method.

[mitchdenny]

Please do some testing with this in the playground just to make sure there are no rough edges here.

[JamesNK]

Even if there are previous app host added args, the double dash could be excluded from what is displayed to the user by not adding it to the custom annotation.