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

compiler/testData/diagnostics/tests/TraitWithConstructor.fir.kt

@@ -0,0 +1,18 @@
+// !DIAGNOSTICS: -MISSING_CONSTRUCTOR_KEYWORD
+
+class C(val a: String) {}
+
+interface T1(val x: String) {}
+
+interface T2 constructor() {}
+
+interface T3 private constructor(a: Int) {}
+
+interface T4 {
+    constructor(a: Int) {
+        val b: Int = 1
+    }
+}
+
+interface T5 private () : T4 {}
+interface T6 private<!SYNTAX!><!> : T5 {}