GAM contextual + Publisher as top level PAAPI seller example

This example starts PAAPI auctions at the same time as GAM targeting. The flow is similar to a typical GAM auction, but if Prebid wins, and got a PAAPI bid, it is rendered instead of the contextual bid.

Instructions

Start Chrome with these flags:

--enable-features=CookieDeprecationFacilitatedTesting:label/treatment_1.2/force_eligible/true --privacy-sandbox-enrollment-overrides=https://localhost:9999

Join interest group at https://publisherdirect.criteo.com/publishertag/examples/cdb/ig-bidding.html?buyer-ig-frame=fake%2520bidder%2520preprod&decision-script=prod&auction-type=single/

Join interest group at https://www.optable.co/

Copied from https://github.com/dgirardi/Prebid.js/blob/361068c856e50e0a5bf8efe311b9d63f074acae4/integrationExamples/top-level-paapi/gam-contextual.html