Faster AbstractArray hashing with a static hash seed (#39950)
Previously, the `object_id` lookup for `hash(AbstractArray, h)` dominated the hashing time for `AbstractArray`:
```
julia> using StaticArrays, BenchmarkTools
julia> a = @SVector [1,2,3,4,5];
julia> @btime hash($a, UInt(0))
77.935 ns (0 allocations: 0 bytes)
0xdeb6d0657a261f74
julia> @btime hash(AbstractArray, UInt(0))
58.643 ns (0 allocations: 0 bytes)
0xc03f1dbe32103a9e
```
This replaces the hash of the objectid with a static randomly-generated
number. Now:
```
julia> @btime hash($a, UInt(0))
18.580 ns (0 allocations: 0 bytes)
0x5e77b8bf73067ebd
```
and for a random `Float64` vector
```
julia> @btime hash($a, UInt(0))
29.031 ns (0 allocations: 0 bytes)
0x9a574d69612587eb
```
Co-authored-by: Milan Bouchet-Valat <nalimilan@club.fr>
