Add Lockdown Mode entitlement and use it in the WebContent sandbox instead of JIT entitlement.
<rdar://problem/110178613>
Pull request: https://github.com/WebKit/WebKit/pull/14635
Committed 264837@main (a646dbce6fc3): <https://commits.webkit.org/264837@main> Reviewed commits have been landed. Closing PR #14635 and removing active labels.
rdar://101821075