Postfix templates: add tests for new templates and use full qualified names

in templates

java/java-tests/testData/codeInsight/template/postfix/templates/opt/intLiteral.java

@@ -0,0 +1,7 @@
+package templates;
+
+public class Foo {
+  void m() {
+    42.opt<caret>
+  }
+}