Fix delegator rewards initialization (Kava-Labs#859)

* fix: sync delegator rewards if they exist before creating new delegation

* remove comments

update changelog (Kava-Labs#856)

fix: check correct time elpased condition (Kava-Labs#853)

fix: calculate reward time elapsed correctly

fix: set indexes to zero (Kava-Labs#835)

Hard Audit: don't convert directly from sdk.Int to uint64 (Kava-Labs#842

)

* refactor away from sdk.Int's .Uint64() method

* refactor cdp module interest calc

check borrow err (Kava-Labs#828)

[R4R] fix: export harvest genesis state (Kava-Labs#778)

* fix: update harvest genesis state to include deposits, claims

* fix migration

Merge branch 'ro-authorized-mempool' into release-v0.12.1