Update event notification ad server variables

[bretg]

Followup to The Event Notification proposal #800

In the original issue, we specified hb_winurl as the ad server targeting variable to use for mobile and AMP scenarios.

Towards reducing the number of bytes that we need to send to the ad server, we're revising the proposal here and in the related Prebid Universal Creative issue prebid/prebid-universal-creative#70

         "ext": {
                        "prebid": {
                            "type": "banner",
                            "targeting": {
                                "hb_winurl": "https://prebid-server.rubiconproject.com/event?t=win&b=BIDID&f=i",
                                "hb_bidid_rubicon": "4b61fbb6-d864-4a36-b3dc-ef860d104601",
                                "hb_bidid_appnexus": "5b61fbb6-d864-4a36-b3dc-ef860d104607",
                                ...
                            }
                       }
            }

The change is that hb_winurl is a template used by the Prebid Universal Creative and BIDID is resolved with the appropriate bidders hb_bidid_BIDDERCODE.

[stale]

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[bretg]

Updated #800 and the tech spec at #1006

We're working on this in PBS-Java now.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.