System controller should reload custom resources without restarting router pods

[nluaces]

Context

Currently the system controller is not watching changes in the custom resources generated as input. To make effective those changes, the command skupper system reload needs to be run, and as a consequence, the router pods are deleted and recreated.

Proposed solution

To avoid this situation, these changes need to be implemented:

• System controller needs to watch all the new files or updated ones on each namespace, and start/reload the sites with changes that cannot be treated dynamically.
• A separate process should watch the changes that can be done dynamically.
• At the same time, static sites (bundles) need to be supported, so dynamic changes will not affect them.
• the system controller container also needs to manipulate systemd services in the host.