This Cl adds a type to {WasmTableObject}, and extends
{WasmTableObject::Set} and {WasmTableObject::Get} to support anyref
tables. I did it in one CL so that I can write tests.

R=mstarzinger@chromium.org

Bug: v8:7581
Change-Id: I6c6d78f84715a7805f7bb881a63d3c1174f6a6ab
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1511332Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60206}