Reorganize GitHub Actions report as a test-report extension

[Evangelink]

Summary

Treats the GitHub Actions report MTP extension as a test-report extension alongside Azure DevOps, TRX, HTML, JUnit, and CTRF, instead of a top-level extension feature. The inline prose in microsoft-testing-platform-features.md is replaced with a dedicated ## GitHub Actions reports section in microsoft-testing-platform-test-reports.md that mirrors the Azure DevOps section structure.

Changes

docs/core/testing/microsoft-testing-platform-test-reports.md

• New ## GitHub Actions reports section (after Azure DevOps): intro + activation behavior, NuGet requirement line, experimental > [!NOTE], ### Manual registration (builder.AddGitHubActionsProvider();), and a ### Options table using the three-column | Option | MTP version | Description | format (all options 2.3.0).
• description: frontmatter now enumerates GitHub Actions.

docs/core/testing/microsoft-testing-platform-features.md

• Removed the top-level **[GitHub Actions report]…** entry from ## Extension features.
• Repointed the ## Choose by scenario bullet to ./microsoft-testing-platform-test-reports.md#github-actions-reports (was the raw NuGet URL).
• Updated the Test reports blurb to TRX, HTML, JUnit, CTRF, Azure DevOps, GitHub Actions.

docs/navigate/devops-testing/toc.yml

• Added GitHub Actions to the Test reports displayName for searchability (no new node; content lives in an existing file).

Content source breakdown

All option names, values, defaults, versions, and the registration call were verified against the extension source in microsoft/testfx (Microsoft.Testing.Extensions.GitHubActionsReport): GitHubActionsCommandLineOptions.cs, GitHubActionsFeature.cs, GitHubActionsExtensions.cs, the package PACKAGE.md, and HelpInfoAllExtensionsTests.cs (help text). Descriptions were adapted from that source and the original features.md prose.

⚠️ Accuracy correction — please confirm

The previous features.md prose said the extension "activates automatically when the GITHUB_ACTIONS environment variable is true, or elsewhere with the --report-gh switch." The authoritative source contradicts this:

GitHubActionsFeature.cs: "The extension activates only when running on GitHub Actions (GITHUB_ACTIONS=true) and the --report-gh master switch is set." (Same statement in PACKAGE.md.)

The new section states that both GITHUB_ACTIONS=true and --report-gh are required. Flagging this in case the runner-side auto-injection of --report-gh (via MSTest.Sdk / MSBuild props) was the intent of the original "automatic" wording — an expert should confirm the final phrasing.

ai-usage: ai-assisted (kept on both files).

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Internal previews

📄 File	🔗 Preview link
docs/core/testing/microsoft-testing-platform-features.md	Microsoft.Testing.Platform (MTP) features
docs/core/testing/microsoft-testing-platform-test-reports.md	Microsoft.Testing.Platform (MTP) test reports
docs/navigate/devops-testing/toc.yml	docs/navigate/devops-testing/toc

[Copilot]

Pull request overview

This PR reorganizes documentation for the Microsoft.Testing.Platform GitHub Actions report extension by treating it as a test-report extension (alongside Azure DevOps, TRX, HTML, JUnit, and CTRF) instead of documenting it as a top-level extension feature.

Changes:

• Added a dedicated GitHub Actions reports section to the test reports article, including activation behavior, manual registration, and an options table.
• Removed the GitHub Actions report’s standalone entry from the features overview and replaced it with a link to the new test-reports section.
• Updated the DevOps testing TOC search keywords to include GitHub Actions under Test reports.

Show a summary per file

File	Description
docs/core/testing/microsoft-testing-platform-test-reports.md	Adds a new “GitHub Actions reports” section and updates frontmatter description to include GitHub Actions.
docs/core/testing/microsoft-testing-platform-features.md	Removes the top-level GitHub Actions report blurb and points scenario guidance to the new test-reports section anchor.
docs/navigate/devops-testing/toc.yml	Improves discoverability by adding “GitHub Actions” to the Test reports displayName keywords.

Copilot's findings

• Files reviewed: 3/3 changed files
• Comments generated: 1

[Evangelink]

Please reapprove @gewarren