Change local KMS to not require Aries storage interface

[DRK3]

This is part of an overall larger storage rework to switch Aries from using the current "one size fits all" approach to data storage to one that allows consumers of Aries-Framework-Go to define their storage layer according to their needs.

The goal of this task is to switch the local KMS implementation to not require an Aries Storage provider. To make the transition easier, a storage wrapper type can be created to allow for a caller to continue using the existing storage implementations while they are working on new ones.