Add hash functions

[vanillajonathan]

Discussed in https://github.com/PRQL/prql/discussions/1768

^{Originally posted by **vanillajonathan** February 10, 2023} Maybe there could be hash functions? Like [SHA-3](https://en.wikipedia.org/wiki/SHA-3), BLAKE or ChaCha20? Example: ```rust let foo = sha3_512("Hello world!") ```

[max-sixty]

We'd need to:

• figure out the correct interface — do we want a hash and then an parameter for the type of hash? Or we just offer sha2 at first, with only a parameter for the value?
• Understand how various dialects implement these. We don't need to cover every single one, but we need to cover most of them for the cases we support
• Write the code in the compiler to get the correct function for each dialect in https://github.com/PRQL/prql/blob/f56b258605fdde961927df3a6b0d6651c89dc647/prql-compiler/src/sql/dialect.rs, and link it to the function.

Brief note:

let foo = sha3_512("Hello world!")

This would be let foo = sha_bar "Hello world!", no parentheses