Context

To compute rights, instead of using snapshots of stakes which makes things hard to reason with, we can use:

for staked tez, the value at the end of the cycle; those tez are going to stay frozen for at least 7 more cycles;
for delegated tez, the minimum over the cycle; if you switched delegate or if you staked during the cycle, then those tez do not bring rights in that cycle.

I think it has the good properties:

not counting twice the same tez,
not bringing rights to people moving tez, hence preventing people buying and selling tez right before the snapshot to gather the rights.

What we lose is the consistency that the sum of rights correspond to the sum of delegated+frozen stake at some point in time.

~~refactoring of Full_staking_balance_repr~~ -> moved to !11086 (merged)
enriching Full_staking_balance_repr to lazily maintain the minimum over the last cycle (probably requires more comments)
using it instead of the snapshot
~~getting rid of the snapshots~~ -> moved to !11374 (merged)
~~cleaning up dead stuff~~ -> moved to !11369 (merged), !11370 (merged), !11374 (merged)

Manually testing the MR

See updated tests.

Some AI tests are still broken, they make assumptions on what the snapshot contains. Leaving the fix to @lrand

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Edited Dec 21, 2023 by Mehdi Bouaziz