Add nominated flag to candidate pair stats

This way we can identify, between the valid candidate, which one has
been nominated.

agent.go

@@ -457,6 +457,7 @@ func (a *Agent) setSelectedPair(p *candidatePair) {
 	a.onSelectedCandidatePairChange(p)
 
 	a.selectedPair = p
+	a.selectedPair.nominated = true
 	a.updateConnectionState(ConnectionStateConnected)
 
 	// Close mDNS Conn. We don't need to do anymore querying
@@ -993,7 +994,7 @@ func (a *Agent) GetCandidatePairsStats() []CandidatePairStats {
 				LocalCandidateID:  cp.local.ID(),
 				RemoteCandidateID: cp.remote.ID(),
 				State:             cp.state,
-				// Nominated bool
+				Nominated:         cp.nominated,
 				// PacketsSent uint32
 				// PacketsReceived uint32
 				// BytesSent uint64

candidatepair.go

@@ -22,6 +22,7 @@ type candidatePair struct {
 	local               Candidate
 	bindingRequestCount uint16
 	state               CandidatePairState
+	nominated           bool
 }
 
 func (p *candidatePair) String() string {

selection.go

@@ -82,6 +82,7 @@ func (s *controllingSelector) ContactCandidates() {
 		p := s.agent.getBestValidCandidatePair()
 		if p != nil && s.isNominatable(p.local) && s.isNominatable(p.remote) {
 			s.log.Tracef("Nominatable pair found, nominating (%s, %s)", p.local.String(), p.remote.String())
+			p.nominated = true
 			s.nominatedPair = p
 			s.nominatePair(p)
 			return