This CL makes the AST type format name match the WGSL name so the
overloaded operator<< can be used in the WGSL writer. This removes a
bunch of duplication of WGSL type format name strings.
Bug: tint:230
Change-Id: I14aaefd21ced267ceed31f21faba3bd291275f0d
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/29402
Reviewed-by: Ryan Harrison <rharrison@chromium.org>
Commit-Queue: dan sinclair <dsinclair@chromium.org>