Add WKKeyedCoder as an alternate code path for WebKit secure coding types (and use it to serialize AVOutputContext)
<rdar://problem/119279237>
Pull request: https://github.com/WebKit/WebKit/pull/21416
Committed 271664@main (361273dff3a1): <https://commits.webkit.org/271664@main> Reviewed commits have been landed. Closing PR #21416 and removing active labels.