Deocde nonce from be bytes

[salman01zp]

Summary of changes

• Decoder from parity_scale_codec expects nonce to be decoded from le_bytes, whereas dkg signs a message in which nonce is converted to be_bytes.

let nonce_from_maintainer = T::MaintainerNonce::decode(&mut &message[..4])
.map_err(|_| Error::<T, I>::InvalidNonce)?;

Therefore, we need to decode nonce directly using from_be_bytes

let mut nonce_bytes = [0u8; 4];
nonce_bytes[0..4].copy_from_slice(&message[..4]);
let nonce_from_maintainer: T::MaintainerNonce = u32::from_be_bytes(nonce_bytes).into();

Reference issue to close (if applicable)

Closes

[drewstone]

Great catch @salman01zp

[shekohex]

That will not compile, it needs to be 1u32.to_be_bytes()