Add content filter related Mach service to the Networking process sandbox.
<rdar://problem/101780002>
Pull request: https://github.com/WebKit/WebKit/pull/12698
rdar://106216542
Committed 262936@main (bdbf8bd332f6): <https://commits.webkit.org/262936@main> Reviewed commits have been landed. Closing PR #12698 and removing active labels.