Useragentdata support

[rowan-m]

Context: #7269

Review requests

• npm run doc complains about [MarkDown] Method Page.setUserAgent() userAgentData Object != UserAgentMetadata. Not really clear how to resolve. Other methods that are using a DevTools protocol type are also just referrring to Object.
• Not sure if you have a preferred convention on setting an optional key in an array. I've erred on the side of being more verbose, but perhaps there's something more elegant to do.

Adds userAgentData to setUserAgent that supports specifying user agent
data for the new navigator.userAgentData and Client Hints headers.

[mathiasbynens]

Thanks for kicking this off, Rowan!

Jan and Alex, could you PTAL?

[OrKoN]

Not sure about npm run doc complains. Perhaps, @jschfflr or @jackfranklin know? For me locally, it complains about Method Page.emulateVisionDeficiency() type string != Object

[jschfflr]

To fix the npm run doc command, you probably have to add an exception to utils/doclint/check_public_api/index.js.
We should probably improve the documentation around this!

[rowan-m]

add an exception to utils/doclint/check_public_api/index.js.

Will test this!

[rowan-m]

@OrKoN @jschfflr I think your comments should be addressed now.

[OrKoN]

LGTM thanks!

[rowan-m]

Tests don't work, fixing.

[jschfflr]

For the failing test you can use npm run eslint-fix to have the linter fix the empty line and add
// eslint-disable-next-line @typescript-eslint/ban-ts-comment above the // @ts-ignore line.

[rowan-m]

Tests should now be passing.

[jschfflr]

It seems like firefox doesn't support this yet - you can exclude this test from being run on FF by using itFailsFirefox instead of it.

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[jschfflr]

@googlebot I consent.

[jschfflr]

@rowan-m I updated the tests to pass but could you include the requested example that Mathias requested?