[JS FIR] Add JS_NAME_CLASH tests for constructors

^KT-64867 Related

compiler/testData/diagnostics/testsWithJsStdLib/name/constructorsWithSameJsName.fir.kt

@@ -0,0 +1,49 @@
+// FIR_DIFFERENCE
+// K1 doesn't detect a clash between constructors in one class.
+// It doesn't seem correct (KT-64976) because it leads to a clash in the generated JS code. K2 works correctly.
+// !DIAGNOSTICS: -OPT_IN_USAGE
+
+@JsExport
+class ClassA {
+    val x: String
+
+    @JsName("constructorA")
+    constructor(y: String) {
+        x = "fromString:$y"
+    }
+
+    @JsName("constructorOther")
+    constructor(y: Int) {
+        x = "fromInt:$y"
+    }
+}
+
+@JsExport
+class ClassB {
+    val x: String
+
+    @JsName("constructorB")
+    constructor(y: String) {
+        x = "fromString:$y"
+    }
+
+    @JsName("constructorOther")
+    constructor(y: Int) {
+        x = "fromInt:$y"
+    }
+}
+
+@JsExport
+class ClassC {
+    val x: String
+
+    @JsName("constructorC")
+    <!JS_NAME_CLASH!>constructor(y: String)<!> {
+        x = "fromString:$y"
+    }
+
+    @JsName("constructorC")
+    <!JS_NAME_CLASH!>constructor(y: Int)<!> {
+        x = "fromInt:$y"
+    }
+}