ci: convert remaining Azure Pipelines PR checks to Github Actions

[Saadnajmi]

Summary:

Move over the remaining jobs from Azure Pipelines to Github Actions. This includes porting over the commented out integration tests. Delete most of the Azure Pipelines code. What should be left is just the release pipeline.

Test Plan:

The CI :D

[Saadnajmi]

@copilot make test-react-native-macos-init and test-react-native-test-app-integration only run on *-stable branches, with a comment that once we are set up to release nightlies, we can test on main.

[Copilot]

Pull Request Overview

This PR migrates the CI/CD pipeline from Azure DevOps Pipelines to GitHub Actions while retaining the Azure release pipeline. The migration includes converting build, test, and integration jobs to GitHub Actions workflows with improved Verdaccio server handling and streamlined toolchain setup.

• Converts PR checks, JavaScript tests, and build/test jobs from Azure Pipelines to GitHub Actions
• Introduces reusable workflow patterns and a centralized toolchain setup action
• Enhances Verdaccio server startup reliability with better error handling and timeout management

Reviewed Changes

Copilot reviewed 29 out of 29 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
.github/workflows/microsoft-pr.yml	Updates main PR workflow to use new toolchain action and adds JavaScript tests, RNTester builds, and integration tests
.github/workflows/microsoft-test-react-native-macos-init.yml	New workflow for testing react-native-macos initialization with Verdaccio setup
.github/workflows/microsoft-react-native-test-app-integration.yml	New workflow for react-native-test-app integration testing
.github/workflows/microsoft-build-rntester.yml	New workflow for building RNTester across multiple platforms and configurations
.github/actions/microsoft-setup-toolchain/action.yml	New reusable action for consistent toolchain setup across workflows
.ado/scripts/waitForVerdaccio.mjs	Enhanced Verdaccio startup script with better error handling and ping endpoint usage
Various .ado/ files	Removed Azure DevOps templates, jobs, and configuration files

Comments suppressed due to low confidence (2)

.ado/scripts/verdaccio.sh:15

• The line calling waitForVerdaccio.mjs is removed from verdaccio.sh, but the new GitHub Actions workflows still call this script with the 'init' command, expecting it to wait for Verdaccio. This will cause the workflows to proceed before Verdaccio is ready.

    scripts_root=$(cd -P "$(dirname $0)" && pwd)