[shuffle] Move val/ to new structure.

This CL moves the val/ files into the `lang/msl/validate` and
`lang/hlsl/validate` folders and updates the includes. The namespaces
and some method names are updated during the move to fit with the new
location. The `val/val.h` header is split into two, one for HLSL and one
for MSL.

Bug: tint:1988
Change-Id: Ie18b5c6a0491aa1d5ff3e3bee143c5d25d8606ce
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/142180
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
diff --git a/src/tint/CMakeLists.txt b/src/tint/CMakeLists.txt
index 222b54a..cbc920e 100644
--- a/src/tint/CMakeLists.txt
+++ b/src/tint/CMakeLists.txt
@@ -885,9 +885,10 @@
 
 ## Tint validation utilities. Used by tests and the tint executable.
 add_library(tint_val
-  val/hlsl.cc
-  val/msl.cc
-  val/val.h
+  lang/hlsl/validate/hlsl.cc
+  lang/hlsl/validate/val.h
+  lang/msl/validate/msl.cc
+  lang/msl/validate/val.h
 )
 
 # If we're building on mac / ios and we have CoreGraphics, then we can use the
@@ -896,7 +897,7 @@
 if(APPLE)
   find_library(LIB_CORE_GRAPHICS CoreGraphics)
   if(LIB_CORE_GRAPHICS)
-    target_sources(tint_val PRIVATE "val/msl_metal.mm")
+    target_sources(tint_val PRIVATE "lang/msl/validate/msl_metal.mm")
     target_compile_definitions(tint_val PUBLIC "-DTINT_ENABLE_MSL_VALIDATION_USING_METAL_API=1")
     target_compile_options(tint_val PRIVATE "-fmodules" "-fcxx-modules")
     target_link_options(tint_val PUBLIC "-framework" "CoreGraphics")