Let the user know that class object bounds are not supported

KT-4080 Code analisys show all good, but got compile error

#KT-4080 Fixed

compiler/testData/diagnostics/tests/generics/ClassObjectBoundsAreNotSupported.kt

@@ -0,0 +1,2 @@
+class C<T> where <!UNSUPPORTED!>class object T: Any<!>
+fun f<T>() where <!UNSUPPORTED!>class object T: Any<!> {}

compiler/testData/diagnostics/tests/generics/kt1575-ClassObject.kt

@@ -1 +1 @@
-class CO<T> where class object T : CO<T>
+class CO<T> where <!UNSUPPORTED!>class object T : CO<T><!>