FNV1a 52 bit

[DRN88]

Hello, great lib thank you.

I was wondering if you could please add 52bit function(s) too.

I am happened to be in a situation where I need to move functionality from javascript to php.
I have FNV1a 52bit used in javascript from this class: https://github.com/tjwebb/fnv-plus/blob/master/index.js
In this class 52bit and 64bit functions are very similar, so maybe it is easy to do for php too (as we have the 64bit one in this repo)

I'm trying to do this myself, if I get it to work I share it here. But I am not that confident I can do this. Could you please have a look?

Thank you

[philippelyp]

FNV1a is not specified for 52 bits. See https://datatracker.ietf.org/doc/html/draft-eastlake-fnv-18