Add a pseudo-random generator directly into the WASM module

[f-aguzzi]

Is your feature request related to a problem? Please describe.
The random numbers used in the k-means clustering algorithm require calls to the WASM runtime through the JS bridge, and this slows down the execution. I propose the addition of a xorshift pseudo-random generator within the Rust code as a speed-up.

Describe the solution you'd like
Something like this:

pub struct Xorshift {
    state: u32,
}

impl Xorshift {
    pub fn new(seed: u32) -> Self {
        Xorshift { state: seed }
    }

    pub fn next(&mut self) -> f64 {
        self.state ^= (self.state << 13);
        self.state ^= (self.state >> 17);
        self.state ^= (self.state << 5);
        self.state as f64 / u32::MAX as f64
    }
}

Describe alternatives you've considered
Leaving it as it is. It doesn't really matter.

Additional context
Нет ничего.