The authenticatorAttachment should be "cross-platform" for hybrid transactions, but is currently always "platform".
<rdar://problem/102608692>
Pull request: https://github.com/WebKit/WebKit/pull/7178
Committed 257576@main (f1464f7963f4): <https://commits.webkit.org/257576@main> Reviewed commits have been landed. Closing PR #7178 and removing active labels.