Test utility to check key metric expectations for a single submission

Verifying Autofill key metrics after a single form submission is a
recurring pattern throughout many tests.

This CL adds a utility to check for expectation for
Readiness, Assistance, Acceptance and Correctness for a single
submission and a parameterizerd form type name.

The code will be used in a subsequent CL.

Bug: 447094853
Change-Id: Idcb7ab41f645688a57a5c0d3fe4fc28ecc7184be
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6973945
Commit-Queue: Matthias Körber <koerber@google.com>
Reviewed-by: Jihad Hanna <jihadghanna@google.com>
Cr-Commit-Position: refs/heads/main@{#1519926}