policy-*: Remove any private binding restrictions for allow-all policy

policy-*: Remove any private binding restrictions for allow-all policy

As we don't have any proper mechanisms in place to perform some
level of authentication on the clients binding to the private extensions,
we will resort to allow that to happen, under the default, allow-all policy.

In the same time we add some helpers for checking which applications can
bind to the private extensions but this is for the deny-all policy.
This also includes cluster-receiver and cluster-dashboard application to
that array, as without it the cluster-demo will not all work when using
the deny-all policy.

Bug-AGL: SPEC-3382

Signed-off-by: Marius Vlad <marius.vlad@collabora.com>
Change-Id: I9ea0d8fd63a323bfcee6aa146a1617aa572d131f