auction key limiter feature

[jsnellbaker]

Type of change

• Feature
• Does this change affect user-facing APIs or examples documented on http://prebid.org?

Description of change

PR for the feature described in: #3800

To enable the feature, add the following to code to the prebid config code on a test page:

pbjs.setConfig({
  targetingControls: {
    auctionKeyCharacterThreshold: 5000
  }
});

If you enable debug mode, you can watch the console logs for some details about which sets of keys are permitted/blocked.

In this initial submission, the prioritization of keys are based on the following factors:

• bids with a deal are given preference over bids w/o a deal
• bids with the higher CPM are given higher preference

Other information

Docs PR pending...

[mkendall07]

LGTM overall, I would like to change the param name to something like auctionKeyMaxChars to be more clear about what it does.