[NI] Consider CS as nullable if one of the types isn't subtype of Any

Note that this isn't fully correct, consider the following situation:

S : T, T : Any?
=> CS(S, T) = T, but for now it will be T?, which is reliable but not so specific as just T

compiler/testData/codegen/box/regressions/nullabilityForCommonCapturedSupertypes.kt

@@ -0,0 +1,14 @@
+val targetArgument = id2(star(), star()) // error
+
+fun <T> id2(x: T, y: T): T = x
+
+fun star(): Sample<*> {
+    return Sample<Int>()
+}
+
+class Sample<out T>
+
+fun box(): String {
+    targetArgument
+    return "OK"
+}