Add docs for the new ways to report build failures and giving hint messages from portfile.cmake

[autoantwort]

For microsoft/vcpkg#30775

[prmerger-automator]

@autoantwort : Thanks for your contribution! The author(s) have been notified to review your proposed change.

[learn-build-service-prod]

Learn Build status updates of commit 19bee10:

✅ Validation status: passed

File	Status	Preview URL	Details
vcpkg/maintainers/functions/vcpkg_fail_with_user_interaction_required.md	✅Succeeded	View
vcpkg/maintainers/functions/vcpkg_user_hint_on_failure.md	✅Succeeded	View
vcpkg/TOC.yml	✅Succeeded	View

For more details, please refer to the build report.

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[prmerger-automator]

PRMerger Results

Issue	Description
Added File(s)	This PR contains added files. New files require human review.
Yaml File(s)	This PR includes changes to .yml file(s) owned by another author.
File Change Percent	This PR contains file(s) with more than 20% file change.

[vicroms]

Drafting until the relevant feature is merged.