Criteo Bid Adapter: converted adapter to oRTB 2.5

[Ticki84]

Type of change

• Updated bidder adapter

Description of change

• Modified request and response models to comply with OpenRTB 2.5 (using the oRTB converter).
• Changed the endpoint to forward requests to a new oRTB 2.5 compliant endpoint.
• Dropped support of undefined sized banner trick in favor of built-in native media type.
• Dropped support of native callback in favor of built-in rendering fn.

Breaking changes and how to migrate (for publishers)

• If you were using undefined sized banner to get native bids:

  • Remove the undefined sized banner from mediaTypes.
  • Define a native object in mediaTypes.

• If you were previously using a native callback:

  • Define the render fn by following Prebid Documentation.
  • Define a native object in mediaTypes.

Additional notes

Even though native requests without asset requirements should be supported, we strongly advised to define some native asset requirements.

[Ticki84]

Pushed a change to use the 2.5 translator instead of moving each field "manually".
Huge thanks for the review @dgirardi !

[Ticki84]

Pushed another change because gdprversion is still an extension field in 2.6.

[Ticki84]

CI seems a bit flakky @dgirardi , let me know if I need to push another empty commit to retrigger the CI.