Define a yang.common version of NetconfError

We currently define YangNetconfError in yang-data-api, but we do not have a yang.common version of this contract.
This limits our ability to tie errors together and define a solid RpcError contract, which still lives in yang.common.

Define a baseline NetconfError interface, which provides the required concept, such that it can be specialized by yang-data-api and possibly by mdsal-binding-api.

The baseline needs to be flexible enough to accommodate both the NETCONF (RFC6241) and RESTCONF (RFC8040) definition of this construct.

The most critical part is error-info, which should map to an AnyDataNode in yang-data-api, with appropriate immutable implementations provided by yang-data-impl.