Add server selections tests for RSGhost

JAVA-4420

Author: jyemin

driver-core/src/test/resources/server-selection/server_selection/Unknown/read/ghost.json

@@ -0,0 +1,18 @@
+{
+  "topology_description": {
+    "type": "Unknown",
+    "servers": [
+      {
+        "address": "a:27017",
+        "avg_rtt_ms": 5,
+        "type": "RSGhost"
+      }
+    ]
+  },
+  "operation": "read",
+  "read_preference": {
+    "mode": "Nearest"
+  },
+  "suitable_servers": [],
+  "in_latency_window": []
+}

driver-core/src/test/resources/server-selection/server_selection/Unknown/write/ghost.json

@@ -0,0 +1,18 @@
+{
+  "topology_description": {
+    "type": "Unknown",
+    "servers": [
+      {
+        "address": "a:27017",
+        "avg_rtt_ms": 5,
+        "type": "RSGhost"
+      }
+    ]
+  },
+  "operation": "write",
+  "read_preference": {
+    "mode": "Nearest"
+  },
+  "suitable_servers": [],
+  "in_latency_window": []
+}