Consolidate Dual render ad paths

[patmmccann]

Type of issue

Two areas of the code base can render an ad

Prebid.js/src/secureCreatives.js

Line 56 in 880b089

if (data && data.adId && data.message) {

and

Prebid.js/src/prebid.js

Line 447 in 2d14b7d

$$PREBID_GLOBAL$$.renderAd = hook('async', function (doc, id, options) {

We've had various problems with these getting out of sync, including #7702 and potentially recording analytics events eg bid_won.

It seems best if we consolidate them, potentially by removing the latter and always forcing the post message into an iframe with the creative in it.

[GLStephen]

I think the first path is for SafeFrames and the second is for non-safe frames. I'm not 100% sure one is compatible in the the environment of the other. I would agree with the desire to remove the "GLOBAL" path though.

[dgirardi]

It's unclear to me how we should deal with some of the differences:

• there is partial, awkward support for CLICKTHROUGH macro substitution (docs, also see this issue). It does not work, and with the current interface cannot work, on safeframe.
• there's hair-raising scraper-targeted markup generated only from renderAd, again not from safeframes.
• the new video module has some ad-hoc support only in renderAd. I think this might become a "normal" renderer (@karimMourra?)