Clean manifest build (#1398)

* Clean manifest build

* newline in gitignore

.gitignore

@@ -28,4 +28,5 @@ package-lock.json
 _book
 docs/html
 .idea
-.vscode
+.vscode
+packages/extension/manifest.json

packages/extension/manifest.json

@@ -1,42 +0,0 @@
-{
-  "author": "polkadot.{js}",
-  "description": "Manage your Polkadot accounts outside of dapps. Injects the accounts and allows signing transactions for a specific account.",
-  "homepage_url": "https://github.com/polkadot-js/extension",
-  "name": "polkadot{.js} extension",
-  "short_name": "polkadot{.js}",
-  "manifest_version": 3,
-  "permissions": ["storage", "tabs", "alarms"],
-  "background": {
-    "scripts": ["background.js"],
-    "type": "module"
-  },
-  "action": {
-    "default_title": "polkadot{.js}",
-    "default_popup": "index.html"
-  },
-  "content_scripts": [{
-    "js": ["content.js"],
-    "matches": ["http://*/*", "https://*/*"],
-    "run_at": "document_start"
-  }],
-  "icons": {
-    "16": "images/icon-16.png",
-    "32": "images/icon-32.png",
-    "48": "images/icon-48.png",
-    "64": "images/icon-64.png",
-    "128": "images/icon-128.png"
-  },
-  "web_accessible_resources": [
-    {
-      "resources": [
-        "page.js"
-      ],
-      "matches": [
-        "*://*/*"
-      ]
-    }
-  ],
-  "content_security_policy": {
-    "extension_pages": "script-src 'self' 'wasm-unsafe-eval'; object-src 'self'"
-  }
-}