Implement ArrayDecoding

[daxpedda]

As discussed on Zulip. Any improvements on the documentation are welcome.

[tarcieri]

On second thought, I'm not sure this is needed because I think what you're trying to do here can already be done by the existing ArrayEncoding trait.

You can write code that's generic with respect to the size of the input array like this:

use crypto_bigint::{ArrayEncoding, ByteArray,UInt, nlimbs};

fn parse_uint<const LIMBS: usize>(bytes: ByteArray<UInt<LIMBS>>) -> UInt<LIMBS>
where
    UInt<LIMBS>: ArrayEncoding
{
    UInt::from_be_byte_array(bytes)
}

[tarcieri]

Okay, I see the problem though. It can't infer LIMBS from the size of the GenericArray, which is what you're trying to do.

This looks OK then but I'll leave some line notes.

[tarcieri]

Thank you!