[NI-TESTS] Add regression tests

^KT-33638 Obsolete

Add test for case mentioned in KT-33629.
Used to be runtime failure instead of error diagnostic.

compiler/testData/codegen/box/regressions/kt33638.kt

@@ -0,0 +1,14 @@
+// !LANGUAGE: +NewInference
+// WITH_RUNTIME
+// KJS_WITH_FULL_RUNTIME
+// IGNORE_BACKEND_FIR: JVM_IR
+
+class Holder(val list: List<String>?)
+
+fun box(): String {
+    val holder1 = Holder(emptyList()) // No problem
+    val holder2 = Holder(if(true) emptyList<String>() else null) // No problem
+    val holder3 = Holder(if(true) emptyList() else mutableListOf()) // No problem
+    val holder4 = Holder(if(true) emptyList() else null) // Compile error
+    return "OK"
+}