[Cocoa] Read protected sample key requrements from sample's CMFormatDescription
<rdar://problem/108162777>
Pull request: https://github.com/WebKit/WebKit/pull/12877
Committed 263254@main (c748ef5450bd): <https://commits.webkit.org/263254@main> Reviewed commits have been landed. Closing PR #12877 and removing active labels.