Add local web server configuration designed for web editor development

Running `npm run serve` in `platform/javascript/` will start
a web server that uses `bin/` as its root folder. This means you
can extract a compiled web editor ZIP in this folder and immediately
be able to test the web editor.

Headers required for the use of SharedArrayBuffer are automatically
added to every response.

(cherry picked from commit 9ef9bfb12c3bfd5eca3de1f1c21705e89bb577a1)

platform/javascript/package.json

@@ -2,9 +2,8 @@
   "name": "godot",
   "private": true,
   "version": "1.0.0",
-  "description": "Linting setup for Godot's HTML5 platform code",
+  "description": "Development and linting setup for Godot's HTML5 platform code",
   "scripts": {
-    "test": "echo \"Error: no test specified\" && exit 1",
     "docs": "jsdoc --template js/jsdoc2rst/ js/engine/engine.js js/engine/config.js --destination ''",
     "lint": "npm run lint:engine && npm run lint:libs && npm run lint:modules && npm run lint:tools",
     "lint:engine": "eslint \"js/engine/*.js\" --no-eslintrc -c .eslintrc.engine.js",
@@ -15,7 +14,8 @@
     "format:engine": "npm run lint:engine -- --fix",
     "format:libs": "npm run lint:libs -- --fix",
     "format:modules": "npm run lint:modules -- --fix",
-    "format:tools": "npm run lint:tools -- --fix"
+    "format:tools": "npm run lint:tools -- --fix",
+		"serve": "serve"
   },
   "author": "Godot Engine contributors",
   "license": "MIT",
@@ -23,6 +23,7 @@
     "eslint": "^7.28.0",
     "eslint-config-airbnb-base": "^14.2.1",
     "eslint-plugin-import": "^2.23.4",
-    "jsdoc": "^3.6.7"
+    "jsdoc": "^3.6.7",
+    "serve": "^13.0.2"
   }
 }

platform/javascript/serve.json

@@ -0,0 +1,21 @@
+{
+    "public": "../../bin",
+    "headers": [{
+        "source": "**/*",
+        "headers": [
+            {
+                "key": "Cross-Origin-Embedder-Policy",
+                "value": "require-corp"
+            }, {
+                "key": "Cross-Origin-Opener-Policy",
+                "value": "same-origin"
+            }, {
+                "key":  "Access-Control-Allow-Origin",
+                "value": "*"
+            }, {
+                "key": "Cache-Control",
+                "value": "no-store, max-age=0"
+            }
+        ]
+    }]
+}