Fix loading container type from Java

Load immutable flexible upper bound for 'Iterable<? super T>'

We load 'Collection<? super CharSequence>' as 'MutableCollection<in CharSequence>'
instead of 'MutableCollection<in CharSequence>..Collection<*>'
because it's obviously not typesafe to use any 'Collection<*>'
as argument for such type.

But there'se nothing bad with loading 'Iterable<? super CharSequence>'
as 'MutableIterable<*>..Collection<*>'. Same for other declarations that have
covariant mutable representation (currently Iterator, ListIterator).

Also there are useful use-cases when it's neccessary to use 'Iterable<*>'
as an argument for parameter with type 'Iterable<? super T>' (see matchers.kt test).

NB: Star-projections appear in examples because types like 'Collection<in CharSequence>'
with conflicting use-site projections are invalid in Kotlin, but they are valid in Java.

compiler/testData/diagnostics/tests/j+k/contravariantIterable.kt

@@ -0,0 +1,20 @@
+// FILE: A.java
+import java.util.*;
+public class A {
+    public static void foo(Iterable<? super CharSequence> x) {}
+    public static void bar(Iterator<? super CharSequence> x) {}
+}
+
+// FILE: main.kt
+
+fun test(x: List<String>, y: List<*>, z: MutableList<*>, w: MutableList<in CharSequence>) {
+    A.foo(x)
+    A.foo(y)
+    A.foo(z)
+    A.foo(w)
+
+    A.bar(x.iterator())
+    A.bar(y.iterator())
+    A.bar(z.iterator())
+    A.bar(w.iterator())
+}