v8: fix load elimination liveness checks

This commit back-ports the implementations of IsRename() and MayAlias()
from the upstream 8.0 branch wholesale. Fixes several bugs where V8's
load elimination pass considered values to be alive when they weren't.

Fixes: https://github.com/nodejs/node/issues/31484

PR-URL: https://github.com/nodejs/node/pull/31613


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Beth Griggs <Bethany.Griggs@uk.ibm.com>