e2label in golang

Labeling tool that substitutes e2label in pure golang

All done thanks to the upstream gexto lib which created the needed set pieces for this: github.com/nerd2/gexto

This is a simplified and slimmed down version of it and it justs has one purpouse: list and change ext4 labels.

usage is the same as upstream e2label:

Usage: e2label <filename> [New label]

Calling it with a filename or device will return the existing label. Calling it with a filename or device and a label will set that label.

Thats it, it doesnt need to be more complex than that.

Done thanks to the Kairos hackweek of 2024.