Add GitHub Actions workflow for Managed Identity WebAPI - Publish to WebApp

[gladjohn]

This workflow automates the build and deployment of the Managed Identity WebAPI to Azure, including steps for restoring dependencies, building the project, publishing the output, and testing the deployed endpoint.

This pull request introduces a new GitHub Actions workflow for automated build and deployment of the Managed Identity WebAPI application. The workflow streamlines the CI/CD process by building, publishing, deploying to Azure, and validating the deployed endpoint.

CI/CD workflow addition:

• Added .github/workflows/deploy-managed-identity-webapi.yml to automate build and deployment of the ManagedIdentityWebApi app when changes are pushed to main.
• Configured steps for code checkout, .NET setup, dependency restore, build, publish, and deployment to Azure Web App using the publish profile secret.

Deployment validation:

• Included a step to test the deployed endpoint by calling the token endpoint and verifying the response contains a specific response - "Access token received. Token Source: IdentityProvider"

Here is a successful run - https://github.com/AzureAD/microsoft-authentication-library-for-dotnet/actions/runs/21925738077

Resource - Web App is in the new IDLABS1 lab.

[neha-bhargava]

Why are we adding this as a workflow?

[gladjohn]

Why are we adding this as a workflow?

Rationale for adding this as a GitHub Actions workflow:

Key Benefits:

- Automated Deployment for Test App: The ManagedIdentityWebApi is a test/dev application used to validate managed identity functionality in MSAL.NET. Automating its deployment ensures it's always up-to-date for testing purposes. We can also remove the sample app testing from release matrix.

- Continuous Validation: The workflow includes a validation step that tests the deployed endpoint, ensuring the managed identity integration works correctly after each change. This catches deployment issues immediately.

Ensured this gets triggered only for changes to main so every PR build does not run this