Show raw headers in mocks

[SuperOleg39]

Problem:

Application make request with two same headers with different values.
Teremock create mock only for last of this headers.

Solution:

Read headers from request.rawHeaders, join duplicates to array, or concatenate with ,, for example:

{
  "request": {
    "url": "...",
    "method": "...",
    "headers": {
      "user-agent": [
        "Mozilla/5.0 (Macintosh; Intel Mac OS X 11_0_0) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/88.0.4298.0 Safari/537.36",
        "node-fetch"
      ]
    },
  },
}

or

{
  "request": {
    "url": "...",
    "method": "...",
    "headers": {
      "user-agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 11_0_0) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/88.0.4298.0 Safari/537.36,node-fetch"
    },
  },
}