Change namespace of tint::type

Move the `tint::type` namespace into `tint::core::type` to better match
the source location and contents.

Change-Id: I2e1ae0ecdffdfcedb8aab1391cdfe2e1453a4741
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/145901
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Dan Sinclair <dsinclair@chromium.org>
diff --git a/src/tint/lang/core/ir/module.h b/src/tint/lang/core/ir/module.h
index 8466f24..f5b638d 100644
--- a/src/tint/lang/core/ir/module.h
+++ b/src/tint/lang/core/ir/module.h
@@ -79,7 +79,7 @@
     void SetName(Value* value, Symbol name);
 
     /// @return the type manager for the module
-    type::Manager& Types() { return constant_values.types; }
+    core::type::Manager& Types() { return constant_values.types; }
 
     /// The block allocator
     BlockAllocator<Block> blocks;