Remove JavaClass.getAllMethods()/getAllFields()

Their behavior is different in PSI and reflection (two things that this
interface is supposed to unify), so there's no point in making it interface
methods, rather we should just walk supertype hierarchy manually

Also make JavaClassImpl.getSupertypes() invoke PsiClass.getSuperTypes(),
because it also contains java.lang.Object for interfaces, which makes
equals/hashCode/toString appear in interfaces' getAllMethods() as well

compiler/testData/loadJava/compiledJavaIncludeObjectMethods/EmptyInterface.java

@@ -0,0 +1,4 @@
+package test;
+
+public interface EmptyInterface {
+}