Java8MapApiInspection: support some scenarios to produce Map.merge (IDEA-163910)

java/java-tests/testData/inspection/java8MapApi/afterMergeSimple.java

@@ -0,0 +1,8 @@
+// "Replace with 'merge' method call" "true"
+import java.util.Map;
+
+public class Main {
+  public void testMerge(Map<String, Integer> map, String key) {
+      map.merge(key, 1, (a, b) -> a + b)
+  }
+}