Add charmcraft.yaml debug_mode to charmed-osm

- Added a debug_mode option to lcm, mon, nbi, pol, and ro charms
- Added a script to prepare pods for debugging:
  - setup .ssh/config to easily ssh from vscode to the pods
- Added a README that explains how to prepare the environment for
testing

Change-Id: Ieb56b565c15e61c68ad000b60897abd27e1eeb0e
Signed-off-by: David Garcia <david.garcia@canonical.com>
diff --git a/installers/charm/mon/config.yaml b/installers/charm/mon/config.yaml
index ee593ff..b8477b1 100644
--- a/installers/charm/mon/config.yaml
+++ b/installers/charm/mon/config.yaml
@@ -93,3 +93,13 @@
       ImagePullPolicy configuration for the pod.
       Possible values: always, ifnotpresent, never
     default: always
+  debug_mode:
+    description: |
+      If true, debug mode is activated. It means that the service will not run,
+      and instead, the command for the container will be a `sleep infinity`.
+    type: boolean
+    default: false
+  debug_pubkey:
+    description: |
+      Public SSH key that will be injected to the application pod.
+    type: string