fix: Tier module fixes and improvements (part 4) (#13)

* Add UnlockingLockup message; update MsgUnlockResponse, GenesisState  and query.proto messages; run proto-go

* Add TestMain and test tier keeper setup

* Cleanup and fix test utils

* Improve logic related to storing/retrieving lockups and unlocking lockups

* Improve keeper logic, handle completionTime/unlockTime edge case, update tests

* Handle Lockups and UnlockingLockups separately in InitGenesis/ExportGenesis, update tests

* Refactor queries and update related tests

* Fix issue in calculateProratedCredit, refactor proratedCredit, update related tests

* Update message server, and all related tests

* Add TestHasUnlockingLockup, update comment in TestInitWithMultipleIdenticalUnlockingLockups

* Add TestGetAllUnlockingLockups

* Add more querier tests

* Update keeper tests