Changed the way the constraints are written in tests

SUBTYPE T Int -> T <: Int

compiler/testData/constraintSystem/declarations.kt

@@ -0,0 +1,14 @@
+fun foo<T, P, E>() = 42
+
+interface A
+interface B : A
+interface C : B
+
+interface Consumer<in T>
+interface Producer<out T>
+
+interface My<T>
+interface Successor<T> : My<T>
+
+interface Two<T, P>
+interface Fun<in T, out R>