Add Mullvad Leta Auto Login setting

* Autologin at extension start
* Add support for FPI (Mullvad Browser PBM)

README.md

@@ -76,6 +76,7 @@ local storage). It will require some manual configuration:
 
 Mullvad Browser Extension requires the following permissions:
 
+- `cookies` to be able to autologin to Mullvad Leta
 - `management` to be able to recommend third party extensions
 - `privacy` to disable webRTC
 - `proxy` to configure and use Mullvad proxy servers
@@ -84,6 +85,11 @@ Mullvad Browser Extension requires the following permissions:
 - `*://*.mullvad.net/*` to get proxy servers list and display your connection information (See
   `Network requests` for details)
 
+  **Optional**
+
+- `webRequest` to automatically login to Mullvad Leta (optional)
+- `webRequestBlocking` to automatically login to Mullvad Leta (optional)
+
 _Permissions are automatically accepted when testing the extension._
 
 ## Network requests
@@ -95,6 +101,11 @@ Two external network requests are made by the extension:
 - `am.i.mullvad.net` to get the connection information (Frequency: each time the popup is started
   and each time the proxy is connected/disconnected)
 
+  **Optional**
+
+- `api.mullvad.net` when Mullvad Leta auto login is used (Frequency: on extension start and/or when
+  auth cookie expires)
+
 _External links are marked with this icon_
 ![External Link icon](https://github.com/feathericon/feathericon/blob/master/src/svg/link-external.svg)