push_classifier_branch's request moves into push_branch, which takes the
forge client, so a test can run it against a stand-in forge. The tests
pin the POST to /repos/o/r/contents and its body: base and new branch,
no force overwrite, the message, the operator as author with the
service account as committer, the base64 content, and update with the
blob sha or create without one.
The page's open-a-PR gating becomes rowsProblem in TryOutTypes.ts,
beside the other form checks. swarm-ui has no test runner, so the
typecheck is the only check on it.
Refs #5259
915364c918