Add hash.XxHash

Also move the non crypto hash funcs into this new package.

This is much faster than e.g. MD5, especially for larger inputs:

```
BenchmarkXxHash/xxHash_43-10         	 9917955	       112.2 ns/op	      56 B/op	       4 allocs/op
BenchmarkXxHash/mdb5_43-10           	 6017239	       204.1 ns/op	      96 B/op	       3 allocs/op
BenchmarkXxHash/fnv32a_43-10         	14407333	        82.30 ns/op	      16 B/op	       1 allocs/op
BenchmarkXxHash/xxHash_4300-10       	 2916892	       409.7 ns/op	      56 B/op	       4 allocs/op
BenchmarkXxHash/mdb5_4300-10         	  159748	      7491 ns/op	    4912 B/op	       3 allocs/op
BenchmarkXxHash/fnv32a_4300-10       	  218210	      5510 ns/op	      16 B/op	       1 allocs/op
```

Fixes #12635

tpl/hash/hash.go

@@ -0,0 +1,93 @@
+// Copyright 2024 The Hugo Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package hash provides non-cryptographic hash functions for template use.
+package hash
+
+import (
+	"context"
+	"encoding/hex"
+	"hash/fnv"
+
+	"github.com/cespare/xxhash/v2"
+	"github.com/gohugoio/hugo/deps"
+	"github.com/gohugoio/hugo/tpl/internal"
+	"github.com/spf13/cast"
+)
+
+// New returns a new instance of the hash-namespaced template functions.
+func New() *Namespace {
+	return &Namespace{}
+}
+
+// Namespace provides template functions for the "hash" namespace.
+type Namespace struct{}
+
+// FNV32a hashes v using fnv32a algorithm.
+func (ns *Namespace) FNV32a(v any) (int, error) {
+	conv, err := cast.ToStringE(v)
+	if err != nil {
+		return 0, err
+	}
+	algorithm := fnv.New32a()
+	algorithm.Write([]byte(conv))
+	return int(algorithm.Sum32()), nil
+}
+
+// XxHash returns the xxHash of the input string.
+func (ns *Namespace) XxHash(v any) (string, error) {
+	conv, err := cast.ToStringE(v)
+	if err != nil {
+		return "", err
+	}
+
+	hasher := xxhash.New()
+
+	_, err = hasher.WriteString(conv)
+	if err != nil {
+		return "", err
+	}
+	hash := hasher.Sum(nil)
+	return hex.EncodeToString(hash), nil
+}
+
+const name = "hash"
+
+func init() {
+	f := func(d *deps.Deps) *internal.TemplateFuncsNamespace {
+		ctx := New()
+
+		ns := &internal.TemplateFuncsNamespace{
+			Name:    name,
+			Context: func(cctx context.Context, args ...any) (any, error) { return ctx, nil },
+		}
+
+		ns.AddMethodMapping(ctx.XxHash,
+			[]string{"xxhash"},
+			[][2]string{
+				{`{{ hash.XxHash "The quick brown fox jumps over the lazy dog" }}`, `0b242d361fda71bc`},
+			},
+		)
+
+		ns.AddMethodMapping(ctx.FNV32a,
+			nil,
+			[][2]string{
+				{`{{ hash.FNV32a "Hugo Rocks!!" }}`, `1515779328`},
+			},
+		)
+
+		return ns
+	}
+
+	internal.AddTemplateFuncsNamespace(f)
+}