Fix `IsAbstract()` so that it doesn't consider most-nested element types.
Add `ElementType()` and `DeepestElementType()` helpers.
Add `OverloadUsesF16` as a helper for https://dawn-review.googlesource.com/c/dawn/+/96722.
Simplifies template code.
Change-Id: Iff5a9a7258caea06e00ee37c29e5298d9c35b799
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/97361
Commit-Queue: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Dan Sinclair <dsinclair@chromium.org>
a253a5f7e7