Refactored out the logic backing the JournalBase TimestampDateTime property so it can be used for any DateTime type property, providing a standardized json String -> DateTime conversion for any date-time property. Implemented as an `internal static` method on JournalBase so journal objects which inherit from JournalBase or don't inherit from it can use it.
Used this to provide a DepatureTimeDateTime on CarrierJumpRequest (this property was added in Update 14) and to implement the existing ExpiryDateTime on CurrentGoal.
From a quick search in the journal documentation, I don't see any other applications for this.
* chore: move all observatory repos to core
* only save journal folder on change, don't constantly re-check during monitoring
* chore: monorepo project changes
* chore: monorepo migration
