Ensure BufferedResponse type is not caching un-released buffer

[anuchandy]

No description provided.

[anuchandy]

The issue:

The BufferedHttpResponse used to cache only references to the source response body buffers. The buffers will be released underneath as first subscription consumes them. For the future subscriptions these released buffers were severed, this result in decoder and other parts depending on BufferedHttpResponse to receive garbage data.

consumers of BufferedHttpResponse:

1. test record interceptor
2. body decoder
3. http logging interceptor

fixes in pr:

1. updates the BufferedHttpResponse to do deep copy caching of source response body buffers.
2. removes BufferedHttpResponse use in "body decoder" (that saves extra allocations)
3. updates StreamResponse::close() such that it won't attempt to dispose already consumed buffer source.

No update in "test record interceptor" and is fine to buffer as this is not used in production.

future

1. we could improve "http logging interceptor" by not doing buffering. This is not included in this PR.

[JonathanGiles]

Looks good to me. Not certain either if my suggestions will work but something to think about applying (and for future coding efforts to cut down on verbosity).

[anuchandy]

@srnagar thanks for the review. @JonathanGiles, thanks - your suggestions work, validated locally so committing them.