[wasm] Introduce helper for calling runtime stubs

This avoids a lot of code repetition for generating the call descriptor
and the actual call for a runtime stub.

R=thibaudm@chromium.org

Bug: v8:11384, v8:11453
Change-Id: Ice5d5513534ee854b50e323d788fa5cb2630e627
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2702336
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72840}