Feature request - Reload configuration on changes

[SkalaNetworks]

Hi,

I have an environment with tons of alertmanagers that can come and go. The karma configuration is handled purely in GitOps.
This means that any change in the configuration is applied directly on the configmap in my Kubernetes.
The thing is Karma doesn't care about configuration changes, it doesn't monitor the config file for new updates.

Having this feature would greatly help in my workflow. Right now we need to restart Karma on every configuration change.
I'm willing to make a PR for this functionality if it is deemed of interest.

Thanks.