Include encoding type when returning the public key

[robdefeo]

Is your feature request related to a problem? Please describe.
A public key can be encoded in various methods, currently it is based in the protocol. This is not clear to the caller what encoding is used and it is not future proof.

Describe the solution you'd like
Including the encoding used for public as per #310

{
    "public_key": "0x369bb60e6d99e30144e8fab8087bd7d171ba7b5dbf691b87319584b3d6c1892c"
    "public_key_encoding": "hex/0x-prefix"
}

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
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