http_logger: collect information from failed round trips

[darrenjaneczek]

What this PR does / why we need it:

To collect information about requests that yield Error.
If available, collect information from the response as well.

If the response is nil, a fake response is constructed from the error object.
Here is an example extracted from an unexpected EOF error:

"response": {
  "status": 0,
  "statusText": "ERROR",
  "httpVersion": "",
  "cookies": [],
  "headers": [],
  "content": {
    "size": 3,
    "mimeType": "",
    "text": "EOF"
  },
  "redirectURL": "",
  "headersSize": -1,
  "bodySize": 3
},
"cache": {
  "comment": "Not cached"
},
"timings": {
  "send": 0,
  "wait": 0,
  "receive": 0
},

[darrenjaneczek]

Currently, this does not work well for nil responses.

[toddtreece]

will this defer need a nil check?

[darrenjaneczek]

Fortunately no. This is old code that I will revert. It is no longer expected to be nil: Callers of this method now send a fake response that encapsulates the error if no response was created.

[darrenjaneczek]

This might have some unexpected consequences.
We are overwriting a nil res, which will later be returned. Perhaps a different variable name.

resToAdd := res