In previous implementation Container service handlers didn't cache the
results of `Get` / `GetEACL` / `List` operations. As a consequence of this,
high load on the service caused neo-go client's connection errors. To avoid
this there is a need to use cache. Object service already uses `Get` and
`GetEACL` caches.
Implement cache of `List` results. Share already implemented cache of Object
service with the Container one. Provide new instance of read-only container
storage (defined as an interface)to morph executor's constructor on which
container service is based. Write operations remained unchanged.
Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>