Implement Polly recording/replaying of requests

Created by: marekweb

Currently the Polly adapter implemented in #13870 is able to intercept and fulfill requests.

It currently doesn't fully implement another Polly feature: recording and replaying requests which are persisted as HAR files.

Support for recording/replaying is partial:

• With the adapter, Polly is able to record and persist requests in HAR files
• But adapter doesn't succeed in fulfilling requests when they are being replayed from the persisted HAR files