Exchange authorization code for ID token and complete SaslOIDCClientConversation framework

After the web server is able to retrieve authorization codes, the shell should launch a HttpClient that connects to the authURL's token endpoint and includes the clientId, clientSecret, and authorization code in the GET request's parameters. Upon retrieving the token in response, the SaslOIDCClientConversation should provide this token as the second step of SASL with the server and handle the response as either authentication success or failure.

For now, we will not write a test to fully validate this flow, but we can assume that this works if we can authenticate using Okta as an IdP with MFA from the shell to the server in a live demo.