Introduce stack setup script

This change introduces setup-stack.sh script which will do setup
for the stack itself such as setting the default scenario if not
specified by the user and more importantly installing the dependencies.

Further changes will be sent, moving dependencies to stacks and
installations of those into stack setup script.

Depends-On: I6b9d27edd2016594b197a368b8ed393e98beef7f
Change-Id: I7892fa217a7db5c0c7b84a1b57aa6f311ee14cc6
diff --git a/vars/kubernetes.yaml b/vars/kubernetes.yaml
index 905bb35..75bd857 100644
--- a/vars/kubernetes.yaml
+++ b/vars/kubernetes.yaml
@@ -55,6 +55,9 @@
   - k8-multus-plugins
   - k8-weave-nofeature
 
+# NOTE (fdegir): set default deploy scenario for the stack
+deploy_scenario: "{{ lookup('env', 'DEPLOY_SCENARIO') | default('k8-multus-plugins', true) }}"
+
 # -------------------------------------------------------------------------------
 # Nordix: Docker version
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