[client] Add unit tests for engine synchronization and Info flag copying

- Introduced tests for the Engine's handleSync method to verify behavior when SkipNetworkMapUpdate is true and when NetworkMap is nil.
- Added a test for the Info struct to ensure correct copying of flag values from one instance to another, while preserving unrelated fields.

shared/management/client/grpc_test.go

@@ -0,0 +1,26 @@
+package client
+
+import (
+    "testing"
+)
+
+func TestGrpcClient_LastNetworkMapSerial_SetGet(t *testing.T) {
+    c := &GrpcClient{}
+
+    if got := c.getLastNetworkMapSerial(); got != 0 {
+        t.Fatalf("initial serial should be 0, got %d", got)
+    }
+
+    c.setLastNetworkMapSerial(123)
+    if got := c.getLastNetworkMapSerial(); got != 123 {
+        t.Fatalf("serial after set should be 123, got %d", got)
+    }
+
+    // overwrite should work
+    c.setLastNetworkMapSerial(5)
+    if got := c.getLastNetworkMapSerial(); got != 5 {
+        t.Fatalf("serial after overwrite should be 5, got %d", got)
+    }
+}
+
+