feat: rewards overhaul

[cdummett]

PR updates the rewards specification with updates defined in the requirements document.

[jeremyletang]

Could we specify the default values for these in the specs?

[cdummett]

Sure @barnabee to confirm these are sensible but for now have set

• rewards.vesting.baseRate=0.1 (means ~50% of rewards are unlocked after 7 epochs and ~95% after 31 epochs)
• rewards.vesting.minimumTransfer=100 (same as the minimum transfer network parameter).

[barnabee]

The minimum transfer means that someone with 1000 of rewards will be fully unlocked after 10 epochs regardless of the baserate. That seems too high.

Additionally I think the base rate ought to suggest unlocking over months rather than days for anyone with non-trivial rewards.

I think the minimum transfer amount should be something like 5 or 10, and the base rate probably in the range 1–2.5%.

However, I think this one we need to discuss with @MM0819 and Steven so lets hold off on confirming anything until that is done.

[gordsport]

@cdummett - can we add some sensible values to both this and the spreadsheet and these will be used. A core isue to be raised to update once the real values have ben decided

[davidsiska-vega]

Looks basically fine, but I've left a couple of tiny comments.

It needs review from Lewis and Steven as they're the ones who have the best picture of how this functionality will be used.