Test-Proxy can optionally compress request/response

[scbedd]

Teams discussion

The test-proxy should support a new flag that be set when StartRecording is being invoked - CompressAtRest. (Working title)

• If set, right before the proxy writes the recording to disk, we should compress the request and response bodies of each entry.
• This means that the request and response payloads on disk will not be human readable
• When loading a recording from StartPlayback, these bodies should be decompressed to their original format.

All of this should be entirely transparent to the users other than:

• The CompressAtRest boolean passed in StartRecording
• The files at rest will have zipped bodies

It's a actually a bit of an interesting question, because the compressed bytes will need to be encoded to some serialized format, and I'm not actually certain if that'll save us space. OR the recording won't be json anymore.