FIR checker: report nullable expression as LHS of class literals

compiler/testData/diagnostics/tests/classLiteral/nonClassesOnLHS.fir.kt

@@ -10,11 +10,11 @@ val l2 = <!NULLABLE_TYPE_IN_CLASS_LITERAL_LHS!>List?::class<!>
 
 fun <T : Any> foo() {
     val t1 = <!TYPE_PARAMETER_IS_NOT_AN_EXPRESSION!>T<!>::class
-    val t2 = <!TYPE_PARAMETER_IS_NOT_AN_EXPRESSION!>T<!>?::class
+    val t2 = <!NULLABLE_TYPE_IN_CLASS_LITERAL_LHS!><!TYPE_PARAMETER_IS_NOT_AN_EXPRESSION!>T<!>?::class<!>
 }
 
 inline fun <reified T : Any> bar() {
-    val t3 = T?::class
+    val t3 = <!NULLABLE_TYPE_IN_CLASS_LITERAL_LHS!>T?::class<!>
 }
 
 val m = Map<String>::class