feat: allow ConfigWatcher to watch several files (#236)

[adietish]

fixes #236

[adietish]

@sbouchet please review.

[adietish]

@sbouchet: please review

[sbouchet]

code looks ok. what's the process to actually test it ? compile locally then use that build in kuberntes with multiple kubeconfig files ?

[adietish]

@sbouchet:
This updated watcher is watching whatever files you give it. It would watch several files if you given it several ones, watch only a single one if you give it a single file only:

1. First thing to do is to use it with the current tooling, openshift and/or kubernetes. I'd change the config file at ~/.kube/config and verify that the toolings reacting to the changes and refresh the trees.
2. In a 2nd step you can then install the maven artifact in your local m2 repo and test it when reviewing Cannot get my clusters to appear intellij-kubernetes#779. That PR makes intellij-kubernetes watch all the files listed in KUBECONFIG= and is passing those to this watcher.
   Instructions are in issuecomment-2277887769 and issuecomment-2265980362.
   I have serveral files: ~/.kube/minikube.yml, ~/.kube/rh-sandbox.yml and ~/.kube/config. The latter only has the property current-config. This property is set to the name of the minikube context defined in the file for minikube (minikube.yml) or context for the RH sandbox that's defined in the file for the RH sandbox (rh-sandbox.yml).

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[sbouchet]

works fine with multiples or single files.