BUG-2304 Fix leafref/instanceIdentifier processing in restconf -> netconf pipeline

Resolve the leafref type based on type being referenced by the xpath.
Fix tests testing wrong instance identifier behavior
Fix subtree filtering in netconf northbound when identityrefs are involved

Change-Id: I561e0c92550dd6639a9f9fbd1909695041c378e4
Signed-off-by: Maros Marsalek <mmarsale@cisco.com>
Merge "BUG-2304 Fix leafref/instanceIdentifier processing in restconf -> netconf pipeline"