tint/utils: Default to using Hasher instead of std::hash

STL std::hash<T*> implementations have a tendency of just reinterpreting the
pointer as a size_t. This is fast, but produces a bad hash, as most pointers
tend to be 4 or 16 byte aligned. The lack of entropy in the LSBs causes
clustering of hashmap slots. Use tint::utils::Hasher to get better hashes.

Change-Id: Ife768d573cd1875e746ca9d77a4ac19e43b06aca
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/99281
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Dan Sinclair <dsinclair@chromium.org>
Commit-Queue: Ben Clayton <bclayton@google.com>

src/tint/utils/hashmap.h

@@ -19,6 +19,7 @@
 #include <optional>
 #include <utility>
 
+#include "src/tint/utils/hash.h"
 #include "src/tint/utils/hashset.h"
 
 namespace tint::utils {
@@ -31,7 +32,7 @@ namespace tint::utils {
 template <typename K,
           typename V,
           size_t N,
-          typename HASH = std::hash<K>,
+          typename HASH = Hasher<K>,
           typename EQUAL = std::equal_to<K>>
 class Hashmap {
     /// LazyCreator is a transient structure used to late-build the Entry::value, when inserted into

src/tint/utils/hashset.h

@@ -23,6 +23,7 @@
 #include <utility>
 
 #include "src/tint/debug.h"
+#include "src/tint/utils/hash.h"
 #include "src/tint/utils/vector.h"
 
 namespace tint::utils {
@@ -39,7 +40,7 @@ enum class AddAction {
 
 /// An unordered set that uses a robin-hood hashing algorithm.
 /// @see the fantastic tutorial: https://programming.guide/robin-hood-hashing.html
-template <typename T, size_t N, typename HASH = std::hash<T>, typename EQUAL = std::equal_to<T>>
+template <typename T, size_t N, typename HASH = Hasher<T>, typename EQUAL = std::equal_to<T>>
 class Hashset {
     /// A slot is a single entry in the underlying vector.
     /// A slot can either be empty or filled with a value. If the slot is empty, #hash and #distance