Hide Monokle icon and pause all extension activity when current project/workspace is not K8s related

[f1ames]

Extracted from #41:

In my opinion we should completely hide Monokle when the plugin is irrelevant to the end-user. Great plugins are transparent and you don't notice they are there.

And going even further, if we want to completely hide Monokle icon, we could detect if project contains any K8s resources. If not just hide all extension related UI. But then it will require a bit smarter approach to restore it when such resources are added. so it's not a quick fix.

Detecting if project is K8s related should be based on K8s manifest files present. If there are no such files Monokle icon should be hidden and all background work (like policy synchronization) paused. The only background process running, would be one checking if any K8s manifests were added.

[olensmar]

just need to make sure that Monokle "kicks in" as soon as any k8s configuration files are added..