feat(android): Add handlePermissions function for plugins to call

[jcesarmobile]

At the moment onRequestPermissionsResult handles the prompt/prompt-with-rationale/denied logic, but since most plugins will overwrite it, that functionality get lost and checkPermissions always returns prompt because of that.

By adding a new handlePermissions function in Plugin class that handles that logic, users can call it on their onRequestPermissionsResult override.