Relation support for multi-charm VNFs

Adds support for establishing relations between charms

Signed-off-by: Adam Israel <adam.israel@canonical.com>
Change-Id: I9a0b7725013e06635875cd824e219ab6a023efb3
diff --git a/tests/charms/layers/native-ci/layer.yaml b/tests/charms/layers/native-ci/layer.yaml
index edc8839..138d9d3 100644
--- a/tests/charms/layers/native-ci/layer.yaml
+++ b/tests/charms/layers/native-ci/layer.yaml
@@ -1,4 +1,7 @@
-includes: ['layer:basic']
+includes:
+    - 'layer:basic'
+    - 'interface:mysql'
+    
 options:
     basic:
         use_venv: false