Propagate attachment events for ARRAY

Propagate attachment events for ARRAY

Fixed regression in :class:`.ARRAY` datatype caused by
:ticket:`3964`, which is essentially the same
issue as that of :ticket:`3832`, where column attachment events
for :class:`.ARRAY` would not be invoked.   This breaks the use case
of using declarative mixins that declare a :class:`.Column` which
makes use of :meth:`.MutableList.as_mutable`.

Change-Id: If8c57615860883837f6cf72661e46180a77778c1
Fixes: #4141