Prebid core: add utility to retrieve user agent client hints

[dgirardi]

Type of change

• Feature

Description of change

This adds a library utility to retrieve UA client hints formatted as an ORTB 2.6 device.sua object.

Note that:

• the browser API seems to be in the early stages, with only Chromium supporting it, and likely subject to change. There are promises involved now and maybe more in the future. For this reason I think it's too early to have Core query it by default, since it's possible for that to become too expensive / invasive at any point in the future.
• the only potential consumer (sspBC) is not sending out an ORTB payload, so it's not easily refactored to use this.

Other information

Closes #8381

[Fawke]

Hi @dgirardi,

The change looks good to me. I know there's a FPD Enrichment module and validation module.

Do we wanna pre-populate device.sua and call this library from that module?

In future, if Core needs to access these client hints values instead of parsing the string, do we have to write another function (possibly in utils.js)?

We would also need to document this.

Thanks.

[dgirardi]

It makes sense to use this from FPD enrichment, I'll update this PR shortly.

I don't understand this:

In future, if Core needs to access these client hints values instead of parsing the string,

which string? I think this could be used directly by core, although it wouldn't make sense to have it as a library then.

[Fawke]

which string? I think this could be used directly by core, although it wouldn't make sense to have it as a library then.

I meant the user agent string. For example, here we are checking for a safari browser.

I don't know if there'll ever be a use case for Core that makes use of userAgent information. So, I think, it's fine to have it as a library.

[osazos]

LGTM

[Fawke]

Hi @dgirardi,

The change looks good. But do we wanna put a note in the Prebid.org docs somewhere to let adapter contributors know about this module, and how to use it?