[tint][intrinsics] Simplify intrinsic table

* Combine the type and number matcher index tables. The usage knows which
  kind of matcher is needed.
* Combine the type and number template structures.
* Change the template matcher from a single matcher index, to a list of
  matchers. This allows templates to match using other templates.
* Remove the validation forbidding the direct use of a matcher in a
  parameter. While this is discouraged for WGSL due to readability of
  diagnostics messages, there's no reason this couldn't be used to
  simplify other definition files.

Change-Id: I86897d49297c3d4b960e1f73c465103593a445d4
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/175242
Commit-Queue: Ben Clayton <bclayton@google.com>
Auto-Submit: Ben Clayton <bclayton@google.com>
Commit-Queue: dan sinclair <dsinclair@chromium.org>
Reviewed-by: dan sinclair <dsinclair@chromium.org>
Kokoro: Kokoro <noreply+kokoro@google.com>