Add support for Vivaldi Browser

Just ran across this command palette extension and it works great for Edge - thanks for making it.

I wonder if it's possible to add support for the Vivaldi Browser (https://vivaldi.com).  The JSON format is very similar to Chrome and stored at C:\Users\<User>\AppData\Local\Vivaldi\User Data\Default\Bookmarks.  

Thanks for considering and happy to help test anything.  