Feat: MessageBooker (#946)

* Feat: added booking of data messages

* Feat: added ApproverType

* Fix: fixed prefix iteration for Approvers

* Fix: temporarily changed TransactionType of payload package

* Feat: added optional ApproverType for Approvers

* Refactor: renamed a method

* Feat: added IsInPastCone (not fully done, yet)

* Feat: added pastconecheck for messages

* Feat: WIPWIPWIPWIP

* WIP2WIP2WIP2

* Fix: execute tests online

* Fix: fixed test

* Fix: fixed some stuff

* Fix: fixed invalid bug

* Fix: fixed test issues on windows

* Fix: fixed last issues with the test

* Refactor: refactored remaining code

* Fix: fixed bug with tipselector

* Fix: fixed solidification

* Refactor: removed extraneous Solidification

* Fix: fixed walker

* Docs: fixed the comment to match the refactor

* Docs: changed docs again

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