Test: Add Value Tangle event tests (#484)

* upgrade hive.go

* upgrade testify

* fix minor errors

* test that the correct events are triggered

* add test for MissingPayloadReceived event

* remove unused PayloadUnsolidifiable event

* fix TODOs

* Fix: fixed wrong testcase

* Fix: fixed wrong pending parameter in tests

* Feat: added missing PayloadInvalid Event

* upgrade testify

* Feat: propagate payload invalid events

* Feat: added error variables

* Refactor: added missing comment for error

* Refactor: final refactor

Co-authored-by: Hans Moog <hm@mkjc.net>