tint/ast: Generate ast::TexelFormat from intrinsics.def

Emit unit tests for parsing and printing.
Emit benchmarks for parsing.
Uses intrinsics.def as a single-source-of-truth.
The generators provide a way to optimize the enum parsers.

Change-Id: I603c2a1bd238eb8d059f3d13238e5e48379de6af
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/97202
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: Dan Sinclair <dsinclair@chromium.org>
Kokoro: Kokoro <noreply+kokoro@google.com>

src/tint/sem/storage_texture.cc

@@ -75,7 +75,7 @@ sem::Type* StorageTexture::SubtypeFor(ast::TexelFormat format, sem::Manager& typ
             return type_mgr.Get<sem::F32>();
         }
 
-        case ast::TexelFormat::kNone:
+        case ast::TexelFormat::kInvalid:
             break;
     }