Monorepo (WordPress#57)

Restructures the repository as monorepo and separates the PHP implementation from the WordPress-specific bits. The new packages:

* **php-wasm** – low-level WASM PHP primitives
    * A configurable PHP build pipeline for different targets (web, node.js, standalone)
    * A low-level `PHP` JavaScript class with `eval` for executing PHP code and FS utils like `writeFile` for runtime managing the
    * A `PHPServer` JavaScript class for dispatching HTTP requests – both to run the PHP files AND to download static files
    * A `PHPBrowser` JavaScript class to consume the above using an iframe
* **php-wasm-browser** – a high-level layer to efficiently run `php-wasm` in the browser
    * `service-worker` utilities to redirect the browser traffic to `PHPServer`
    * `worker-thread` utilities to offload the `PHPServer` to a separate process. Three backends are available: Iframe, Webworker, SharedWorker.
    * A messaging layer and setup helpers to connect the above.
    * Server utilities to serve the correct headers for the `wasm` files via `.htaccess`.
* **wordpress-wasm** – WordPress-specific WASM PHP bindings for web and node.js
    * The required WordPress-specific setup like constants and filters
    * `wp.data` bundling pipeline for the web configurable to bundle custom code
    * WordPress API to ease common tasks like login, install a plugin, start a block editor with specific settings and content
    * A `fetch`-based transport for HTTP requests
    * An example app demonstrating WordPress in the browser. Let's eventually extract it into a separate package or at least a directory.

Other, general notes:

* Pre-built binaries are shipped in the global `build` directory – it would be nice to either move them to their specific packages, or remove them from the repo completely and download them from somewhere on the initial build.
* `esbuild` is used to build each packages and then the entire app.
* Gulp is used for orchestration. Perhaps https://nx.dev/ would make a good replacement in the future.
* There is no package publishing process yet. Perhaps Lerna would make a good one?

Solves WordPress#51 and WordPress#16

.eslintignore

@@ -1,6 +1,3 @@
 node_modules/**/*
-wasm-build/**/*
-dist-web/**/*
-dist-node/**/*
-src/node/wordpress/**/*
-node-php.js
+build/*
+packages/*/build*/*

.gitignore

@@ -1,16 +1,16 @@
 .DS_Store
 .idea
+.local
 node_modules
 package-lock.json
-wasm-build/php/docker-output/*
-!wasm-build/php/docker-output/.gitkeep
-wasm-build/wordpress-data/docker-output/*
-!wasm-build/wordpress-data/docker-output/.gitkeep
-wasm-build/wordpress-data/preload/wordpress*
-dist-web/wp-lazy-files.js
-dist-web/service-worker.js
-dist-web/wasm-worker.js
-dist-web/app.js
-dist-web/*.html
-dist-web/wp-lazy-files.js
-
+build/*
+!build/wp-admin
+!build/wp-content
+!build/wp-includes
+!build/php.wasm
+!build/php-web.js
+!build/php-webworker.js
+!build/wp.data
+!build/wp.js
+packages/*/build*
+packages/*/build*/*

.prettierignore

@@ -1,6 +1,3 @@
 node_modules/**/*
-wasm-build/**/*
-dist-web/**/*
-dist-node/**/*
-src/node/wordpress/**/*
-node-php.js
+build/*
+packages/*/build*/*

README.md

@@ -36,7 +36,7 @@ npm run build:php:node
 ## Building custom WordPress bundle
 
 If you'd like to customize the packaged WordPress installation, update
-the build script at `wasm-build/wordpress-data/prepare-wordpress.sh`. It generates a bundle called `wp.data`.
+the build script at `packages/wordpress-wasm/wordpress/prepare-wordpress.sh`. It generates a bundle called `wp.data`.
 
 For example, before the comment "Prepare WordPress static files":
 

build/.htaccess

@@ -0,0 +1,11 @@
+AddType application/wasm .wasm
+
+RewriteEngine on
+RewriteRule ^scope:.*?/(.*)$ $1 [NC]
+
+<FilesMatch "iframe-worker.html$">
+  Header set Origin-Agent-Cluster: ?1
+</FilesMatch>
+
+RewriteEngine on
+RewriteRule ^plugin-proxy$ plugin-proxy.php [NC]