feat: add sources

[stringhandler]

The sources here are manually generated.

I originally generated these using Haskell, as seen in my original repo, however that is controversial, so I've just included the sources for now.

The code can be tested by cloning this into a local folder, and then using a program like:

use std::assert::assert_eq8;

fn main() {

    let a: u8 = 1;
    let b: u8 = 2;

    assert_eq8(a, b);
}

Compile with simc program.simf --dep std=<path_to_local_folder>

e.g. simc program.simf --dep std=~/projects/simplicityhl-std/src