Add Lighthouse benchmarks

[MackinnonBuck]

Add Lighthouse benchmarks

This PR includes the following changes:

• Added Lighthouse testing job
  • Runs against the specified URL, so it's a general-purpose job that's not tied to a specific application
  • Allows for running Lighthouse multiple times and averaging the results
  • Allows an additional "warm-up" run so that the tests run against a fully initialized server
    • Note: The warm-up does not affect the client. We currently clear the Chrome cache between each run, but we could consider adding tests that run against a client cached assets.
  • Tests the following metrics:
    • First Contentful Paint
    • Interaction to Next Paint †
    • Largest Contentful Paint
    • Total Blocking Time
    • Time to Interactive
• Added a "Run template" job
  • Creates, publishes, and runs a project created from an arbitrary project template
  • It's set up in a way that makes it easy to add additional template scenarios (only .yml config changes required)
• Added Lighthouse scenarios for the Blazor Web App template:
  • Includes:
    • With Server interactivity
    • With WebAssembly interactivity

Still TODO:

• Add more Lighthouse scenarios
  • Blazor Web App with Auto interactivity
  • Blazor WebAssembly standalone
• † Add support for Lighthouse user flows. This will allow us to collect metrics for scenarios other than loading pages (e.g., typing into a text field, clicking a button/link, etc.).
• Utilize the changes from Add measurements api dotnet/crank#703
• Document how to run these benchmarks locally

Fixes dotnet/aspnetcore#29303

[sebastienros]

Pending changing source branches to main
Next PR will be adding it to the CI