Revert "This CL updates the cmake files to use go run directly."

This reverts commit a950d4539e.

Reason for revert: Ran into issues integrating into all the required build environments.

Original change's description:
> This CL updates the cmake files to use go run directly.
>
> Instead of using the tools/run script this CL updates CMake
> to directly invoke go run. This should work around issues
> with multiple writers of the gen binary and fixup windows issues.
>
> Change-Id: Ie27f45a1d132e9ec100cad709bb92da8558b4fb3
> Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/108045
> Reviewed-by: Ben Clayton <bclayton@google.com>
> Kokoro: Kokoro <noreply+kokoro@google.com>
> Commit-Queue: Dan Sinclair <dsinclair@chromium.org>

TBR=dsinclair@chromium.org,bclayton@google.com,noreply+kokoro@google.com,dawn-scoped@luci-project-accounts.iam.gserviceaccount.com

Change-Id: I10e7796d4f11661f2055c08202c84e56355ec397
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/108420
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Dan Sinclair <dsinclair@chromium.org>

src/tint/CMakeLists.txt

@@ -510,9 +510,8 @@ function(tint_generate TARGET)
         ${PROJECT_SOURCE_DIR}/src/tint/intrinsics.def
         ${CMAKE_CURRENT_SOURCE_DIR}/${TARGET}.tmpl
     )
-    set(GEN_CMD ${PROJECT_SOURCE_DIR}/tools/golang/bin/go run ./tools/src/cmd/gen)
     add_custom_command(
-        COMMAND ${GEN_CMD} -o ${DAWN_BUILD_GEN_DIR} ${PROJECT_SOURCE_DIR}/src/tint/${TARGET}.tmpl
+        COMMAND ./tools/run gen -o ${DAWN_BUILD_GEN_DIR} ${PROJECT_SOURCE_DIR}/src/tint/${TARGET}.tmpl
         DEPENDS ${IN}
         OUTPUT ${DAWN_BUILD_GEN_DIR}/src/tint/${TARGET}
         COMMENT "Tint: Generating files for ${TARGET}"