Enable payout verification while doing SOLO mining

[GitGab19]

After we merge stratum-mining/sv2-apps#497, we can enable payout verification every time user selects SOLO mining.

We simply have to enable the new verify_payout parameter in tProxy's config file.

[GitGab19]

Moving this to the next milestone, since without backporting stratum-mining/sv2-apps#497 on the older apps' versions, this feature would work only for users running Bitcoin Core v31.

After the work on bitcoin_core_sv2 (defined here), we will be able to always use the same apps' versions for every Bitcoin Core version the user is running.

So it makes sense to wait for those changes to land on sv2-apps before introducing the feature here.

[GitGab19]

Blocked by stratum-mining/sv2-apps#516