This adds a reflective function to retrieve the function type of an
exported or constructed WebAssembly function object. Note that this
first implementation only supports exported functions for now, the
support for constructed functions will be done as a follow-up.

R=jkummerow@chromium.org
TEST=mjsunit/wasm/type-reflection
BUG=v8:7742

Change-Id: I38a16972d8437521993992ca20887c47c7c6b99b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1627989Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61851}