Ensure we're utilizing full SHA256 digests in our Address types

[james-chf]

Currently we only use the first 40 bytes of the 64 byte hex encoding of the 32 byte SHA256 digest. We should instead use all of the digest i.e. the entire 32 bytes, not hex encoded.

e.g. when generating an EstablishedAddress

namada/shared/src/types/address.rs

Lines 372 to 386 in d1a06a2

	pub fn generate_address(
	&mut self,
	rng_source: impl AsRef<[u8]>,
	) -> Address {
	let gen_bytes = self
	.try_to_vec()
	.expect("Encoding established addresses generator shouldn't fail");
	let mut hasher = Sha256::new();
	let bytes = [&gen_bytes, rng_source.as_ref()].concat();
	hasher.update(bytes);
	// hex of the first 40 chars of the hash
	let hash = format!("{:.width$X}", hasher.finalize(), width = HASH_LEN);
	self.last_hash = hash.clone();
	Address::Established(EstablishedAddress { hash })
	}

Also see #112 for extra context