using for: self transportType to create package handler
using for: LegacvPackageHandler extracted
commitChannels extracted
refactored default commit path per transport type
commit-related things are all in through *Importer-Exporter
DRYing through Package>>transport
Renamed tests.

They in fact do not do anything interesting with Package.
They test functionality of LegacyPackageHandler.

The tests should be moved. They are not Kernel tests.