DodoApp: Support volume requests

Users can define volumes section under app, and for each volume
corresponding env variable will be passed down to the application.

Change-Id: I8da9d5e1ca652cdb2f0196fcba1b6242064d057f
diff --git a/charts/app-runner/values.yaml b/charts/app-runner/values.yaml
index 9ec9b55..97e793f 100644
--- a/charts/app-runner/values.yaml
+++ b/charts/app-runner/values.yaml
@@ -8,3 +8,4 @@
 appDir: /dodo-app
 appPort: 8080
 manager: ""
+volumes: []