Finish initial github login flow

Also:
- fix github teams query: fix bug and sort/unique the results
- add IDP display name to github downstream subject
- fix error types returned by LoginFromCallback
- add trace logs to github API results
- update e2e test
- implement placeholder version of refresh for github

test/testlib/skip.go

@@ -1,4 +1,4 @@
-// Copyright 2020-2023 the Pinniped contributors. All Rights Reserved.
+// Copyright 2020-2024 the Pinniped contributors. All Rights Reserved.
 // SPDX-License-Identifier: Apache-2.0
 
 package testlib
@@ -33,3 +33,11 @@ func SkipTestWhenActiveDirectoryIsUnavailable(t *testing.T, env *TestEnv) {
 		t.Skip("Active Directory hostname not specified")
 	}
 }
+
+func SkipTestWhenGitHubIsUnavailable(t *testing.T) {
+	t.Helper()
+
+	if IntegrationEnv(t).SupervisorUpstreamGithub.GithubAppClientID == "" {
+		t.Skip("GitHub test env vars not specified")
+	}
+}