Nexx360: Preserve custom imp.ext fields and add vendor id#4359

CTMBNara merged 2 commits intomasterprebid/prebid-server-java:masterfrom

nexx360-preserve-custom-ext-fields-and-add-gvlidprebid/prebid-server-java:nexx360-preserve-custom-ext-fields-and-add-gvlidCopy head branch name to clipboard