IX: Incorrect Handling of FledgeAuctionConfig in Bidder Response

[oronno]

The PR #2807 attempted to implement handling of FledgeAuctionConfig for IX bid responses but introduced an incorrect implementation. The IX server response places the auction config in ext.protectedAudienceAuctionConfigs field as an array of object (not map keyed with string). Thus paapi response is currently getting discarded.

Expectation:
The IX Bidder should correctly generate FledgeAuctionConfig based on the following ext response structure for paapi:

"ext": {
    "protectedAudienceAuctionConfigs": [
      {
        "bidId": "imp_id",
        "config": {
          "someKey": "someValue",
        }
      }
    ]
  }

Reference:

• https://github.com/prebid/prebid-server/blob/master/adapters/ix/ix.go#L294
• https://github.com/prebid/Prebid.js/blob/master/modules/ixBidAdapter.js#L1781
• https://docs.prebid.org/dev-docs/modules/paapi.html#output-values