Base64 Optimization

[neotheprogramist]

• optimization of previous base64 encoding algorithm to use less gas
• direct base64 encoding from felt252

[0xLucqs]

can you add numbers here plz. At least gas and ideally steps/builtins

[piniom]

@LucasLvy

1. The change to the encoding of Array. Testing on an array of 32 bytes (most use-cases) the old implementation uses 7317558 gas while the new one uses only 804588. It is more than 9 times less. Both implementations have linear complexity so changing the length of the data doesn't affect the relative improvement as tested.
2. Encoding of felt252. The use-case that led to the development of this part was that we needed to encode the transaction hash to base64. Directly encoding the hash (felt252) instead of writing it as an Array of length 32 in big endian and then encoding leads to a 2.2x improvement (or 11.6x when using the old array encoding function).

[0xLucqs]

Either say why the unwraps are safe or remove them and switch to results plz