Restart BotKube pod if configmap is updated

[PrasadG193]

Is your feature request related to a problem? Please describe.
BotKube pod should be automatically restarted if someone edits the botkube-configmap in runtime so that BotKube controller starts using with the updated config. This will reduce effort of redeploying complete BotKube stack just for minor configuration changes

Describe the solution you'd like
We already have informers registered to watch lifecycle events of resources, we can catch changes in botkube-configmap and exit if is is updated. Deployment controller will automatically create a new BotKube pod.

[PrasadG193]

We are using https://github.com/fsnotify/fsnotify to get local file change events instead of handling k8s configmap events.