Deprecate usage of authtoken parameters in providers

When SRBAC is completely implemented according to the current spec,
each service user no longer has full admin privilege but has access
limited to the actual requirement. This means that we are no longer
able to use service users to create resources.

This change is a prep-work to get rid of usage of the service user,
currently loaded from authtoken parameters in the .conf file. Now
each providers loads clouds.yaml file placed in /etc/openstack/puppet.

Depends-on: https://review.opendev.org/806474
Depends-on: https://review.opendev.org/828025
Change-Id: I55436944a6cdeca7786cd07580d21643094d2d8e

lib/puppet/provider/neutron.rb

@@ -23,6 +23,7 @@ class Puppet::Provider::Neutron < Puppet::Provider::Openstack
   end
 
   def self.neutron_request(service, action, error, properties=nil)
+    warning('Usage of keystone_authtoken parameters is deprecated.')
     properties ||= []
     @credentials.username = neutron_credentials['username']
     @credentials.password = neutron_credentials['password']

releasenotes/notes/provider-deprecate-at-params-d688fca46bafe562.yaml

@@ -0,0 +1,16 @@
+---
+deprecations:
+  - |
+    The following resource types have been using the credential written in
+    the ``[keystone_authtoken]`` section of ``neutron.conf``. However this
+    behavior has been deprecated and now these resource types first look for
+    the yaml files in ``/etc/openstack/puppet``. Make sure one of
+    ``clouds.yaml`` or ``admin-clouds.yaml`` (which is created by
+    puppet-keystone) is created in that directory.
+
+    - ``neutron_network``
+    - ``neutron_subnet``
+    - ``neutron_port``
+    - ``neutron_router``
+    - ``neutron_router_interface``
+    - ``neutron_security_group``