Factored out the locking logic from the base Holding interface to a separate interface called
Lockable of the Daml.Finance.Interface.Util package.
Updated the Daml.Finance.Interface.Holding.Factory to use a key, employing a Reference
template and the HoldingFactoryKey data type. Additionally, It also requires the Disclosure.I
and has a getKey method and Remove choice.
Removed the requirement that a Fungible.I requires Transferable.I.