Changes:
- Introduce {TypeDefinition} for wasm modules.
- Introduce an enum {TypeDefinition::Kind} to represent the three
  different definition types.
- Collapse the {types}, {type_kinds} and {supertypes} vectors into a
  single vector of {TypeDefinition}s.
- Use {TypeDefinition} in WasmModuleBuilder.
- Drive-by: Remove {kNullIndex} in WasmModuleBuilder.
- Drive-by: Tidy-up wasm-module.h.

Change-Id: I97c2c268bcad745176243c693cf169bfa5714f94
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3416233Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Manos Koukoutos <manoskouk@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78813}