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

compiler/testData/diagnostics/tests/smartCasts/varnotnull/plusplusMinusminus.fir.kt

@@ -0,0 +1,21 @@
+// !WITH_NEW_INFERENCE
+fun foo(arg: Int?): Int {
+    var i = arg
+    if (i != null && i++ == 5) {
+        return i-- + i
+    }
+    return 0
+}
+
+operator fun Long?.inc() = this?.let { it + 1 }
+
+fun bar(arg: Long?): Long {
+    var i = arg
+    if (i++ == 5L) {
+        return i<!INAPPLICABLE_CANDIDATE!>--<!> + i
+    }
+    if (i++ == 7L) {
+        return i++ <!INAPPLICABLE_CANDIDATE!>+<!> i
+    }
+    return 0L
+}