support for some hash function like crc32

[geekfirstty]

I want to use crc32 hash function in remap, can you provide support for this.

[jszwedko]

I think this would be a reasonable addition. If anyone wants to take a shot at this the implementation of the md5 function should be a good reference: https://github.com/vectordotdev/vrl/blob/main/src/stdlib/md5.rs

(I moved this issue to the VRL repository since it is asking for a new function)