Updating the audience network adapter to be 3.x compliant

[robertrmartinez]

Adding back the audience network adapter and updating it to be compliant on 3.x.

You can see a diff from the 2.x and 3.x versions at the revision history of this GIST:

https://gist.github.com/robertrmartinez/cc4cc72fd1445f0096775aac36305583/revisions

[bretg]

@lovell - we'd like you to have a chance to review and approve this PR. Thanks.

[bretg]

Thanks for providing the gist with the diffs.

[robertrmartinez]

I tested the 2.x and 3.x versions on an actual page and was able to see the request to Facebook go out and the same query params were passed (And the resolved pageurl sent is the same:

2.x Request:

https://an.facebook.com/v2/placementbid.json?placementids[]=1033648490040978_1709080755831078&adformats[]=300x250&testmode=false&pageurl=http%3A%2F%2Fwww.rubitest.com%3A8000%2Ftest_pages%2Fsanity%2FTEMP%prebid-test.html%3Fpbjs_debug%3Dtrue&sdk[]=6.0.web&adapterver=1.3.0&platform=241394079772386&platver=2.44.4-pre&cb=a4b4f9fe-adb6-45e5-96ae-cf24d3d597b2

3.x Request:

https://an.facebook.com/v2/placementbid.json?placementids[]=1033648490040978_1709080755831078&adformats[]=300x250&testmode=false&pageurl=http%3A%2F%2Fwww.rubitest.com%3A8000%2Ftest_pages%2Fsanity%2FTEMP%prebid-test.html%3Fpbjs_debug%3Dtrue&sdk[]=6.0.web&adapterver=1.3.0&platform=241394079772386&platver=3.4.0-pre&cb=03410156-2cb2-4598-a322-0c5c676c1a59

[jsnellbaker]

LGTM

[bretg]

Going ahead to merge this as many are waiting on it. The testing done looks reasonable to me. @lovell , we'd still invite you to review the change.

[lovell]

Thanks for restoring this adapter. There's a new version coming along soon but this will provide a stopgap for those wanting to use it with Prebid.js v3.