Adapt to the new and improved reward strategy

[autholykos]

What is this for

This is a followup after dusk-network/rusk#614

[ureeves]

The payload of the coinbase, in the context of this change, will be:

pub struct CoinbasePayload {
    pub block_height: u64,
    pub generator: PublicKey,
}

[herr-seppia]

@ureeves

I know we discussed these change together, but a question just raise in my mind:
How can the explorer show information about the block reward without derive them using txs fees and block height?

[ureeves]

In my view this should be computed from the transaction fees and the block height. If we don't want to use those - and I would ask why not - we could have Rusk return said information to the consensus program. Maybe some additional information in the return of a state transition?

[herr-seppia]

It's just a matter of making infos explicitly available in the block.
If we want to go for derive them, we don't need to change anything in the block header (Generator and blockheight are already there)

Btw including those info in the header and as return of EST&co should enforce checks by dusk-blockchain during the block acceptance (I'm saying "enforce" because everything is implicitly checked by the statehash match)