graphdb: pass context to GraphSession

graph/db/interfaces.go

@@ -156,7 +156,8 @@ type Store interface { //nolint:interfacebloat
 	// GraphSession will provide the call-back with access to a
 	// NodeTraverser instance which can be used to perform queries against
 	// the channel graph.
-	GraphSession(cb func(graph NodeTraverser) error, reset func()) error
+	GraphSession(ctx context.Context,
+		cb func(graph NodeTraverser) error, reset func()) error
 
 	// ForEachChannel iterates through all the channel edges stored within
 	// the graph and invokes the passed callback for each edge. The callback