start abstract method
Starts a user authentication flow.
The flow screens are presented in a sandboxed browser view that's displayed by this
method call. The method then waits until the authentication completed successfully,
at which point it will return an AuthenticationResponse as in all other
authentication methods. Provide this call with a flowUrl
where the flow
is hosted, and optionally a deepLinkUrl
if targeting Android. This is the URL
that needs to be called by Descope in order to return a result from the flow.
This result URI should then be processed by the exchange function.
Implementation
Future<AuthenticationResponse> start(String flowUrl, {String? deepLinkUrl});