Modularize zkBob pool and add energy redeemer example

[k1rill-fedoseev]

This PR simplifies logic of core ZkBobPool contract, by extracting limits, accounting, and KYC logic into an external contract.

Changelog

Changes in the ZkBobPool interface:

• zkBobPool.getLimitsFor(...) -> zkBobPool.accounting().getLimitsFor(...)
• zkBobPool.kycProvidersManager() -> zkBobPool.accounting().kycProvidersManager()
• All admin functions for managing limits, tiers and KYC are also moved to accounting module
  Changes in denomination:
• Admin function accounting.setLimits(...) now expects values in zkBob units, without denominator

Migration details

There are a few data structures that are being deprecated during the migration:

• Pool stats: slot0 and slot1. These should be copied to the new module during the migration.
• Tier limits. This should be re-initialized in the new module during the migration.
• KYC Manager configuration. This should be re-initialized in the new module during the migration.
• User tiers. These should be re-initialized in the new module during the migration.
• Pool daily usage counters. These can be safely skipped during the migration, as they are not meant to be persistent.
• Auxiliary snapshots. These can be safely skipped during the migration, with little to no impact to maxWeeklyAvgTvl and maxWeeklyTxCount stats.

[akolotov]

Does it make sense to copy this state from the pool contract during initialisation rather than specify them manually?

[k1rill-fedoseev]

I didn't want to include logic for raw storage reads in the main contract, so instead I placed it in the one-time migration contract. I think it's a bit safer and flexible approach overall.

In case we will ever again need to redeploy accounting module (e.g. to change limits logic), such generic initialization logic would be also helpful.

[akolotov]

Does it make sense to call recordOperation from the queue contract directly? What is the goal of having this functionality in the pool contract?

[k1rill-fedoseev]

I think it's better to keep it this way, to reduce dependencies between pool modules. It potentially simplifies future upgrades, as there less address pointers being used between various contracts and permission logic in contract becomes simpler.