CTV Ad Format Signaling Updates

[wittjill]

As part of releasing the CTV Ad Format Guidelines, the Ad Format Hero Taskforce put forth the following signaling design: https://github.com/InteractiveAdvertisingBureau/Ad-Format-Guidelines-for-Digital-Video-CTV/blob/main/Signaling-Implementation-Guidelines.md

It includes:

• AdCOM enumerated list updates
• Native API placement enumerations update (https://github.com/InteractiveAdvertisingBureau/Native-Ads/tree/develop)
• ORTB Implementation Guidelines Pointer (Update implementation.md for CTV Ad Formats openrtb2.x#176)