POC: Plugin Management/Installer Container for Headlamp

[Faakhir30]

This PR is just a Proof of Concept for me to understand better how this problem should be approached.

Upstream issue: kubernetes-sigs#2787

Video demo of current state of my POC:
Screencast from 2025-02-15 20-32-04.webm

Things achieved so far:

• make a config template
• support accepting config file in CLI
• containerize headlamp plugins CLI
• add a plugins Init container, get plugins.yml from values.yml using configMaps.
• install plugins in a emptyDir vol.
• in core headlamp container in same pod, load config from that specific vol.
• Add loggings for better monitoring of plugins installation events.
• Try out PV for production ready
• ..

IMP: This PR is neither meant to be merged, nor created on upstream repo, it was intentionally created on same forked repo, since, its just a POC for my better understanding, I am not following any best coding practices, design practices, documentations, etc here.