Add disable_provider_selection kwarg to Api.authenticate_url

[PickertJoe]

Is your feature request related to a problem? Please describe.
When forcing authentication against a given provider, we want to prevent our users from escaping the auth flow
and selecting a provider from hosted auth main menu that we don't support. Passing the disable_provider_selection=true
query param to the /oauth/authorize endpoint removes the button, but the current implementation of the authentication_url wrapper method does not accept a keyword argument for this param, preventing us from using it.

Describe the solution you'd like
I'd like to add a disabled_provider_selection: keyword argument to the authentication_url method defined on line 38 of lib/nylas/api.rb. I'd then include it in the params object that you're encoding at the end of your call to the /oauth/authorize endpoint.

Describe alternatives you've considered
The only alternative for us at this point is building a call directly to /oauth/authorize endpoint in our Nylas API client. But considering that we're using the SDK's method for all other API calls, we'd like to avoid this convention-breaking change.