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

in templates

java/java-tests/testData/codeInsight/template/postfix/templates/opt/doNotExpandOnJavaLess8.java

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