Feature: SHA256

[balladyna]

The purpose of this branch is to remove the crypto library created by Dart developers from the codec_utils library. It also ensures the independence of codec_utils from our other library - cryptography_utils. This will prevent a recursive dependency between them. The SHA256 algorithm is used in Xoshiro (pseudorandom number generator) and Base58 (encoding scheme).

List of changes:

• created a_hash.dart, to serve as an abstraction for cryptographic hash functions by managing the conversion of byte input into a digest
• created a_hash_sink.dart, to efficiently process streaming hash input by handling incoming data in chunks, managing buffering and ensuring correct endian formatting
• created digest.dart, to represent the final output of hashing algorithm
• created digest_sink.dart, to ensure that only the first received digest is stored, preventing overwrites
• created a_sha_32bit_sink.dart, sha256.dart and sha256_sink.dart, to initialize the digest state, configure hash - computation, define a block size and provide hashing logic for SHA-256