Add hash.XxHash

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