Support Blueprints v2 on playground.wordpress.net

[adamziel]

Let's support the Blueprints v2 runner on playground.wordpress.net.

Minimal required work

• Support "Platform overrides" to support specifying PHP version, landing page, login status
• [Website] Report Blueprint v2 progress #2674
• [PHP Worker] listen to all PHP instances events via worker.addEventListener() #2673
• [Blueprints] Separate computing the runtime configuration from compiling a Blueprint #2672
• [Website] Flatten the stored runtime configuration format #2671
• [Client] Expose Blueprints v2 runner via a feature flag #2658
• [Website] Add Blueprint v2 handlers (noop) #2657
• [Website] Isolate resolveBlueprintFromURL() calls #2654
• Declare the correct Blueprints v2 types #2655
• [Blueprints] Separate computing the runtime configuration from compiling a Blueprint #2672
• [Website] Split Playground remote initialization logic into Blueprint-version specific workers #2652
• [Client] Explicit Blueprints v1 handler #2651
• [Blueprints] Log step names without parsing #2649
• [Blueprints] Rename Blueprints v1 types, add Blueprint v2 types #2648
• [Blueprints] Rename BlueprintDeclaration to BlueprintV1Declaration #2645
• [Blueprints] Move Blueprints v1-specific files to v1 subdirectory #2644
• [Web Client] Remove onBeforeBlueprint #2622
• Move runBlueprintV2 to the blueprints package #2594
• [PHP] Expose php.cli() on the web #2590
• [PHP] Include CLI SAPI in the web PHP.wasm build #2589
• [PHP] Rotate the spawn handler in hotSwapPHPRuntime() #2588

Ready for consumption by developers

• Documentation (Blueprint v2 docs page #2515)
• Prettier progress messages
• Compatibility with the Blueprints builder
• Make sure the download progress is reflected as we go, not all at once at the end of the download
• Reduce the size of blueprints.phar from 2MB to ~100KB by removing double bundling and using the browser's URL parser instead of the rowbot library.

Nice to haves

• Thorough testing
• Use the minified WordPress releases instead of always downloading the full version
• Add a modal "Blueprints v2 integration is still experimental, only proceed if you know what you're doing"?
• Once we're feature-complete, remove the feature flag and make v2 the default Blueprints runner. Or decide to keep it optional indefinitely if the in-browser fetch() pipeline is too slow.
• [Blueprints] Install WordPress without WP-CLI php-toolkit#151
• Heads up to @akirk for compatibility with the step library
• Update the developer documentation, w.org/playground, https://github.com/WordPress/blueprints
• CI job to refresh the blueprints.phar build using a PR for CI tests – similar to dependabot
• Backport recent PRs to Blueprints v1 Allow installing multiple themes via URL, as required by parent/child themes. #2581 Fetch the WordPress.org API to determine Theme/Plugin names. #2580

What did I miss? cc @WordPress/playground-maintainers @griffbrad @wojtekn