[FIR-TEST] Add new testdata generated after changes in previous commit

compiler/testData/diagnostics/tests/dataFlowInfoTraversal/BinaryExpressionElvis.fir.kt

@@ -0,0 +1,16 @@
+// !CHECK_TYPE
+
+fun foo(x: Int?): Int = x!!
+
+fun elvis(x: Number?): Int {
+    val result = (x as Int?) ?: foo(x)
+    checkSubtype<Int?>(x)
+    return result
+}
+
+
+fun elvisWithRHSTypeInfo(x: Number?): Any? {
+    val result = x ?: x!!
+    <!INAPPLICABLE_CANDIDATE!>checkSubtype<!><Int?>(x)
+    return result
+}