[shuffle] Move utils to new structure.

This CL moves the utils folder into the `core` folder and
updates the includes. The namespaces and build groups are not updated in
this CL, just the code move.

Bug: tint:1988
Change-Id: I781545ca24c6f8af208d382db41a9e07b0c20858
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/142161
Reviewed-by: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
diff --git a/src/tint/program_builder.h b/src/tint/program_builder.h
index 16964a7..c8244c9 100644
--- a/src/tint/program_builder.h
+++ b/src/tint/program_builder.h
@@ -27,6 +27,7 @@
 #include "src/tint/builtin/interpolation_type.h"
 #include "src/tint/builtin/number.h"
 #include "src/tint/constant/manager.h"
+#include "src/tint/core/string.h"
 #include "src/tint/lang/wgsl/ast/alias.h"
 #include "src/tint/lang/wgsl/ast/assignment_statement.h"
 #include "src/tint/lang/wgsl/ast/binary_expression.h"
@@ -103,7 +104,6 @@
 #include "src/tint/type/u32.h"
 #include "src/tint/type/vector.h"
 #include "src/tint/type/void.h"
-#include "src/tint/utils/string.h"
 
 #ifdef CURRENTLY_IN_TINT_PUBLIC_HEADER
 #error "internal tint header being #included from tint.h"