Enhance aspire sdk dump

[Copilot]

Addresses PR review feedback on the aspire sdk dump enhancements. Cleans up the format option API, adds diagnostic logging, and fixes minor code quality issues.

Description

--format <value> replaces --json/--ci flags

Consolidates two boolean flags into a single --format option consistent with other CLI commands (ps, describe, mcp tools, etc.):

aspire sdk dump --format json                    # machine-readable JSON
aspire sdk dump --format ci -o capabilities.txt  # stable text for diffing
aspire sdk dump                                  # default pretty output

Accepts Pretty (default), Json, or Ci — case-insensitive.

Other fixes

• AtsCapabilityScanner: Log via Debug.WriteLine when a malformed XML doc file is encountered (previously silently swallowed).
• DotNetBasedAppHostServerProject: Remove unnecessary allAdditionalSources = new List<string>(channelSources) copy — use channelSources directly.
• AtsCapabilityScannerTests: Add Assert.NotNull(first) before Assert.Same in the XML doc cache test to prevent a vacuous pass when the XML file isn't present.
• SdkDumpCommandTests: Replace the now-obsolete --json --ci conflict test with a parameterized theory covering all valid --format values and case variants.

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.dev issue:
      • New issue
  • No

---

🔒 GitHub Advanced Security automatically protects Copilot coding agent pull requests. You can protect all pull requests by enabling Advanced Security for your repositories. Learn more about Advanced Security.