Begin
data class BeginOAuthFlow(val service: String, val scopes: List<String>, val entrypoint: String) : FxaEvent
Begin an oauth flow
If successful, the state machine will transition the FxaState::Authenticating. The next step is to navigate the user to the oauth_url and let them sign and authorize the client.
This event is valid for the Disconnected, AuthIssues, and Authenticating states. If the state machine is in the Authenticating state, then this will forget the current OAuth flow and start a new one.