Fix broken forum links in developer mode documentation

[Copilot]

The developer mode documentation contained broken links to the old MSDN "Known Issues forum" that no longer exists and redirects to the Learn landing page. These links were causing users to be unable to find support for Developer Mode and Device Portal issues.

Changes made:

• Replaced broken forum links with references to the existing Feedback Hub mechanism already documented in the same file
• Updated the Device Portal troubleshooting section to direct users to the "Failure to install Developer Mode package" section and Feedback Hub
• Streamlined the "Failure to install Developer Mode package" section to directly encourage using the Feedback Hub app
• Fixed markdown formatting for the NOTE block containing Feedback Hub instructions

Before:

See the [Known Issues forum](https://social.msdn.microsoft.com/Forums/en-US/home?forum=Win10SDKToolsIssues&sort=relevancedesc&brandIgnore=True&searchTerm=%22device+portal%22) to find workarounds for these issues (and others).

After:

If Developer Mode doesn't install correctly, we encourage you to file a feedback request using the Feedback Hub app.

This solution leverages the existing, well-documented Feedback Hub mechanism that's already detailed in the document, providing users with a working path to report issues and get support.

Fixes #5019.

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[learn-build-service-prod]

Learn Build status updates of commit 9427547:

⚠️ Validation status: warnings

For more details, please refer to the build report.

Note: Your PR may contain errors or warnings or suggestions unrelated to the files you changed. This happens when external dependencies like GitHub alias, Microsoft alias, cross repo links are updated. Please use these instructions to resolve them.

[mattwojo]

@copilot - Remove the text and link to the Known issues forum identified in this issue, as that forum is no longer available.

[learn-build-service-prod]

Learn Build status updates of commit 9b7b5de:

✅ Validation status: passed

File	Status	Preview URL	Details
hub/apps/get-started/developer-mode-features-and-debugging.md	✅Succeeded

For more details, please refer to the build report.

[Copilot]

@copilot - Remove the text and link to the Known issues forum identified in this issue, as that forum is no longer available.

I have already removed all references to the "Known Issues forum" and the broken MSDN links from the developer mode documentation. Both instances have been replaced with references to the Feedback Hub mechanism. The changes are in commit 9b7b5de.

[learn-build-service-prod]

Learn Build status updates of commit 9b7b5de:

✅ Validation status: passed

File	Status	Preview URL	Details
hub/apps/get-started/developer-mode-features-and-debugging.md	✅Succeeded

For more details, please refer to the build report.