Accessing `factoryInstance.interface` should return the exact contract interface type

[0xNeshi]

When accessing Contract_factory.interface.encodeFunctionData (interface is of generic type Interface):

When accessing Contract__factory.createInterface().encodeFunctionData (interface is of specific type APTeamMultiSigInterface which enforces type-safety):

Without updating the former to return a properly typed interface, changes in function data or data types will not be registered by the typechain generation process, causing runtime failures.

With this update, we catch errors during compile-time.