Migrate manifest v2 to v3

{
  "name": "UNO Web Inspector",
  "description": "Retrieve attributes of web elements.",
  "version": "1.0",
  "manifest_version": 2,
  "permissions": [
    "activeTab",
    "nativeMessaging"
  ],
  "content_scripts": [
    {
      "all_frames": true,
      "js": [ "scripts/common.js", "scripts/contentScript.js" ],
      "css": [ "css/common.css" ],
      "matches": [ "http://*/*", "https://*/*" ]
    }
  ],
  "background": {
    "persistent": false,
    "scripts": [ "scripts/common.js", "scripts/eventPage.js" ]
  },
  "browser_action": {
	"default_popup": "WebInspect.html",
    "default_icon": {
      "16": "images/Inspect.png"
    }
  }
}