Support external browser to open OAuth callback

Some sites, like Twitch, do not particularly like being embedded in Electron. ![grafik]( (It says "Your browser is currently not supported", and it just completely blocks any login attempt, and it has been like that for a few months now. I don't assume it will ever come back) For this reason, there could be a minimalistic HTTP server embedded into Insomnia that will be used as callback URL that can be used as a callback URL that works in external browsers. • The port to listen to could be parsed from the redirect URL. - If the URL uses the https:// protocol, probably just return an error in the first iteration of this feature. • When a new token needs to be requested, the OAuth authorization URL could be opened in an external browser. • When redirected to the page served by Insomnia, the query parameters from the URL can then be parsed as normal. • The page itself doesn't really need to show much, other than maybe <h1>A…