Core: support for expandable / flex slots

[dgirardi]

Type of change

• Feature

Description of change

This adds better support for banner slots with flexible sizes:

• publishers can now specify an ortb format array instead of sizes for an ad unit's mediaTypes.banner; expdir can also be supplied there for convenience (alias of ortb2Imp.banner.expdir);
• bid adapters can reply with wratio/hratio instead of width and height;
• because many adapters expect specific sizes, format elements that only specify wratio/hratio are translated to "placeholder" sizes (e.g. {wratio: 2, hratio: 1} becomes [2, 1]);
• creatives now attempt to expand to all the available width/height when rendering a bid that has no definite size.

Other information

#9361

[JulieLorin]

shouldn't we check that w AND h aren't null or wratio AND hratio aren't null ? Instead of having just one non null value

[jsnellbaker]

From what I can tell, I think this looks good. As I mentioned in the last PMC, I don't have a real flex creative to test with - so hopefully another reviewer would be able to check that aspect.

[patmmccann]

@JulieLorin could you weigh in? Thanks! Is your feedback addressed

[JulieLorin]

@JulieLorin could you weigh in? Thanks! Is your feedback addressed

It is ! LGTM

[github-actions]

Tread carefully! This PR adds 26 linter errors (possibly disabled through directives):

• modules/debugging/bidInterceptor.js (+26 errors)

[github-actions]

Tread carefully! This PR adds 18 linter errors (possibly disabled through directives):

• modules/debugging/bidInterceptor.js (+18 errors)