IDEA-65583:

insert import when completing a class reference with existing generics
on tab, replace the generics, if any

java/java-tests/testData/codeInsight/completion/normal/ClassNameWithGenericsTab2.java

@@ -0,0 +1,8 @@
+import java.util.ArrayList;
+import java.util.List;
+
+public class Foo {
+    public static void main(String[] args) {
+        List<Integer> set = new ArrayLis<caret>t<Integer>();
+    }
+}