Synacormedia: Renames to "imds", mirrors prebid-server-go features, adds GPP macros

[ecammit]

Synacormedia: Renames to "imds" and updates the endpoint configurations to match the latest. (see: prebid/prebid.github.io#4237)

• The endpoint config now mirrors the golang prebid-server
• Imds uses a single endpoint hostname instead of a dynamic hostname, for efficiency of open connections (see: PBS2.0: bidders with dynamic hosts prebid-server#2612)
• Imds uses https to allow HTTP/2 negotiation
• Marks synacormedia as a deprecated alias for later removal using the deprecated-names functionality.

Core: Fixes deprecated-names feature to correctly evaluate bidder names from request.imp[].ext.prebid.bidder.* instead of request.imp[].ext.*.

No other bidder seems to be using deprecated-names, so the bug has gone un-noticed since the original pull request (#169) was merged. Upon fixing this, I now receive the expected value in the response:

  "ext": {
    "errors": {
      "synacormedia": [
        {
          "code": 2,
          "message": "synacormedia has been deprecated and is no longer available. Use imds instead."
        }
      ]
    },

If you would like this bug fix split into a separate pull request, I can do that.

[And1sS]

please, use final keyword everywhere where variable is not reassigned. Also, please, check for similar occurences.

[ecammit]

Resolved