Following T337944: Implement support for requesting client hint header, we collect User-Agent Client Hint header data for POST requests associated with edits for logged-in and anonymous users, as well as POST requests for certain Special page actions (logging in, emailing users, etc). See https://www.mediawiki.org/wiki/Extension:CheckUser/Client_Hints and https://wikitech.wikimedia.org/wiki/User-agent_client_hints for some more details.

In this task, we can determine what, if anything, we want to do about including this client hint data in WebRequest logs.

Some prior art is in this patch, although, that patch reverted work which requested client hint data on *all* requests, whereas we only request client hint headers in a subset of all requests.