feat: enable webextension builds

Currently only supports Chrome due to no `chrome` -> `browser` polyfill

package.json

@@ -42,10 +42,14 @@
   "dependencies": {
     "@types/chrome": "^0.0.270",
     "base64-inline-loader": "^2.0.1",
+    "crx": "^5.0.1",
     "css-loader": "^7.1.2",
     "css-to-string-loader": "^0.1.3",
     "extract-loader": "^5.1.0",
     "jsonc-loader": "^0.1.1",
+    "mini-css-extract-plugin": "^2.9.2",
+    "postcss-loader": "^8.1.1",
+    "postcss-url": "^10.1.3",
     "style-loader": "^4.0.0",
     "to-string-loader": "^1.2.0",
     "url-loader": "^4.1.1"