This extends existing table support to be able to store 'exnref' in
addition to 'anyref' types. Tools can use this to maintain data
structures for exception packages.

R=ahaas@chromium.org
TEST=mjsunit/wasm/exceptions-anyref
BUG=v8:8091

Change-Id: Iccbcfdc328db81a366921bcdd98c2256f66e7fc8
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1781046
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64323}