Explore how to reward all active jurors in a given term

[izqui]

A couple of interesting mechanisms (like having a participation rate target) to incentivize juror participation would require having a way to reward all the jurors that were active at a given term. Some options:

• Checkpointing the sum tree, to allow historical queries for its state at any term. This would also remove the need of rescheduling disputes when their draft transaction doesn't occur during the term. Checkpointing would make tree transitions even more expensive to maintain gas-wise.

• Using EVM Storage Proofs: would require performing an account proof of the Court at least every term (at the same block number that we request the randomness for). It would break when multiple term transitions occur in the same block (as the storage proofs can only look at the storage of a contract after all transactions in a block have been processed).

An immediate first step would be to save the total number of tokens that are active for a term in the term state, and then figure out a way for distributing rewards proportionally among jurors.