WebAssembly.Exception is the static representation of a wasm exception.
It holds the signature and the tag of the exception, can be imported and
exported from a wasm module, and will eventually allow inspecting a
wasm-thrown exception from JS.

R=clemensb@chromium.org

Bug: v8:8091
Change-Id: Ided352777e1217e6f873b84a2fc21c3acf59ff6c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2966384Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Thibaud Michaud <thibaudm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#75214}