[NI] Support fixation to subtype in completion mode calculator

Allow full compltion mode for return type depending on type parameters in
contravariant position only if they have proper equality constraint.

compiler/testData/diagnostics/tests/inference/completion/transitiveConstraint.kt

@@ -0,0 +1,15 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_VARIABLE
+
+interface Bound
+interface Upper : Bound
+class Lower : Upper
+
+class Inv<T>
+
+fun <T : Bound, U : T> makeInv(v: U): Inv<T> = TODO()
+fun <K> id(arg: K): K = arg
+
+fun test(lower: Lower) {
+    id<Inv<Upper>>(makeInv(lower))
+}