Add various tests for DFA testing

compiler/tests-spec/testData/diagnostics/notLinked/dfa/neg/31.kt

@@ -0,0 +1,21 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_VARIABLE -UNUSED_VALUE -VARIABLE_WITH_REDUNDANT_INITIALIZER
+// SKIP_TXT
+
+/*
+ * KOTLIN DIAGNOSTICS NOT LINKED SPEC TEST (NEGATIVE)
+ *
+ * SECTIONS: dfa
+ * NUMBER: 31
+ * DESCRIPTION: Raw data flow analysis test
+ * HELPERS: classes, objects, typealiases, functions, enumClasses, interfaces, sealedClasses
+ */
+
+// TESTCASE NUMBER: 1
+fun case_1(x: Interface1) = x
+fun case_1(x: Interface2) = x
+fun case_1() {
+    val x: Interface1 = null <!CAST_NEVER_SUCCEEDS!>as<!> Interface1
+    x as Interface2
+    <!OVERLOAD_RESOLUTION_AMBIGUITY!>case_1<!>(<!DEBUG_INFO_EXPRESSION_TYPE("Interface1 & Interface2")!>x<!>)
+}