Fix mismatches in message fields between specs & implementation

[pythcoiner]

This PR unify the messages fields name between specs & implementation.

In SetCustomMiningJob:

• mining_job_token -> token
• coinbase_tx_input_nSequence -> coinbase_tx_input_n_sequence

In AllocateMiningJobToken.Success:

• coinbase_tx_outputs -> coinbase_output

In DeclareMiningJob:

• coinbase_tx_prefix -> coinbase_prefix
• coinbase_tx_suffix -> coinbase_suffix

In SubmitSolution the field version was not defined

In SetNewPrevHash:

• nBits -> n_bits

I've kept the actual implementation naming in order to not create breaking changes on messages struct signature.

[GitGab19]

Why not simply fixing names in our implementation?
I wouldn't change specs in this case tbh

[pythcoiner]

Why not simply fixing names in our implementation? I wouldn't change specs in this case tbh

i've first try to avoid breaking changes, but yeah it more clean on a long term POV