MV3 Proxy Auth with webRequestAuthProvider

[Tom Riley]

Previously in MV2 I'd been using a "blocking" listener for webRequest.onAuthRequired to provide auth when challenged by proxy servers. In MV3 we get the new webRequestAuthProvider so we can still do auth the same way. 

But as we're doing something like the synchronous example here that keeps track of pending auth requests: https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/webRequest/onAuthRequired#examples

...we need webRequest.onErrorOccurred and webRequest.onCompleted so as to not keep repeatedly supplying the same creds if a proxy challenges again for the same request.

This means we need both webRequest and webRequestAuthProvider permissions. But aren't the other two webRequest listeners going away on MV3 or are those still going to be available?