* Add accumulators
* Move accumulator back to keeper package
* Add earn specific accumulators
* Move store methods to sub-package
* Move earn accumulator
* Rename accumulator files
* Add store doc comment
* Add earn accumulator tests, panic if accumulator not used with earn claim type
* Update earn accumulator tests to use new methods
* Add staking test for earn accumulator
* Add test for accumulator proportional rewards
* Remove old copy of GetProportionalRewardsPerSecond
* Add test for basic accumulator
* Fix AddIncentiveMultiRewardPeriod replacement
* Deduplicate base earn reward accumulator
* Check errors in tests
* Validate RewardPeriods in Params.Validate()
* Use adapter to fetch earn total shares
* Update incentive test to use beginblocker instead manual accumulation
* Update integration test suite
* Add base integration test, wip staking reward calculation
* Get actual staking reward amounts from BeginBlocker events, calculate expected indexes
* Simplify event parsing
* Add initial earn accum test with real keepers
* Add the rest of the accum integration tests with real keepers
* Check if delegation rewards are zero before transferring
* Update staking integration test to use updated methods
