Nested selection of reversed collections fails

The following test fails caused by the fact we make reversed a type that wraps the underline type

@Test
    public void testMapsReversed() throws Throwable
    {
        createTable("CREATE TABLE %s (" +
                    "   k int, " +
                    "   c frozen<map<text, int>>, " +
                    "   v int, " +
                    "   PRIMARY KEY(k, c)" +
                    ") WITH CLUSTERING ORDER BY (c DESC)");

        execute("SELECT c['testing'] FROM %s");
    }

With the error

org.apache.cassandra.exceptions.InvalidRequestException: Invalid element selection: c is of type frozen<map<text, int>> is not a collection

When you look in a debugger you see that the real type is ReversedType(MapType(…)), so the current checks fail.

Additional information for newcomers:

• The problem impact element selection as well as range selection that where introduced in CASSANDRA-7396 as part of 4.0. So the patch will need to be done for 4.0.
• The checks that needs to be modified is in Selectable.WithElementSelection and Selectable.WithSliceSelection
• The unit tests should be added to CollectionsTest