* Misc fixes
detail:
* Fix de-serialisation for account leafs
* Update node recovery from unit tests
* Remove `LegacyAccount` from `PayloadRef` object
why:
Legacy accounts use a hash key as storage root which is detrimental
to the working of the Aristo database which uses a vertex ID.
* Dissolve `hashify_helper` into `aristo_utils` and `aristo_transcode`
why:
Functions are of general interest so they should live in first level
code files.
* Added left/right iterators over leaf nodes
* Some helper/wrapper functions that might be useful
* Provide transaction based interface for standard operations
* Provide unit tests for new Aristo interface using transactions
details:
These new tests combine and replace several single-purpose tests.
The now unused test sources will be kept for a while to be eventually
removed.
Jordan Hrycaj