Refine member scope for types with projections

Instead of erasing descriptors with conflicting substitution,
use invariant CapturedType(<projection>) as replacement for type parameter
within default member scope.

After substitution leave such types 'as is' everywhere except return types,
use common approximation for them.

 #KT-9294 In Progress
 #KT-5411 Fixed
 #KT-8647 Fixed

 #KT-9462 Fixed
 #KT-9893 Fixed
 #KT-7581 Fixed
 #KT-7296 In Progress

compiler/testData/diagnostics/tests/generics/projectionsScope/kt8647.kt

@@ -0,0 +1,8 @@
+interface Subscriber<T>
+
+interface Observable<T> {
+    fun subscribe(s: Subscriber<in T>)
+}
+
+fun foo(o: Observable<out CharSequence>, y: Subscriber<in CharSequence>) = o.subscribe(y) // type safe
+