Parsing: secondary constructors

compiler/testData/psi/secondaryConstructors/basic.kt

@@ -0,0 +1,17 @@
+class A {
+    constructor() {}
+
+    val x: Int
+
+    private annot constructor(x: Int) {}
+
+    [constructor] fun constructor() {}
+
+    annot protected constructor(x: Int, y: Int) : this(1,2) {}
+
+    [constructor] public constructor() : super() {
+        x = 1
+    }
+}
+
+constructor class B