Algod types TEAL byte keys and byte values as strings and base64 encodes them in responses. There was some discussion in algorand/go-algorand#5492 about changing the types on algod, but we decided against it.

This PR updates the types client side so that users don't need to manually decode base64 strings.

A few byte conversion operations were cleaned up as well in the example files.

Relies on algorand/generator#79 to update the generated REST models.