Create a byte_array scheme

[JorikSchellekens]

Allow users to input bytearrays efficiently by defining a byte array scheme.

Example:

starkli invoke eth transfer 0x1234 string:"A long string which should be serialised to a byte array"

The scheme should be either string or a specific string encoding such as utf8

[glihm]

May depends on xJonathanLEI/starknet-rs#522 to have a starknet-rs underlying type to convert to.

[ZackAttax]

Is there a current work around for a byte array as an argument? My constructor uses two bye arrays and I'm getting Failed to deserialize param when I try to deploy.