Improve failed YANG patch error output

On data Patch request processing (see PatchDataTransactionUtil.patchData(…))

• each operation is processed in a sequence, per-operation status is registered

• if there was no per-operation error then commit() is called, commit error is registered as a global error

For case when error occurs on commit the result displays global error together with per-operation status (all success) which is confusing and self contradicting.

Expected: I there is a global error then per-operation status should be omitted (dropped) bc it always displays all successes

Scope: JsonPatchBodyWriter + XmlPatchBodyWriter, ensure behavior is covered by unit tests.