allow to implement and override default methods in java 8 (IDEA-103180) [roma]

(cherry picked from commit 6fc2a889a092365431b92d7f03b8d2057a82d8be)

java/java-tests/testData/codeInsight/overrideImplement/beforeOverrideExtensionMethods.java

@@ -0,0 +1,7 @@
+interface A<T> {
+    default void m(T t) { }
+}
+
+class MyClass<T> implements A<T> {
+    <caret>
+}