Refactor error objects to hold additional data.

The current kv error objects are simply a wrapper around a singular code.  This does not allow us to store additional information such as KV Error Map messages or Enhanced Error Message contexts.  The SDK should be refactored such that error objects can hold additional contextual information.  Note that in the first variant of this implementation, the error objects should remain static and a later commit can be introduced to optional enable dynamic errors (this is for backwards compatibility reasons).