Print labels with their colors on lab label list

[zampierilucas]

This takes the label.Color hex and converts it to color in HexToRGB in utils, then uses is to set the background color.

Closes: https://github.com/zaquestion/lab/issues/887

[zampierilucas]

This is what the labels look like with the change.

[teto]

as a go noob , I was not able to run the PR from the folder via MYGITLABREPO $ go run ~/lab/main.go -- label list because it couldn't find the go modules so I tried go build -o toto -mod=readonly but it asked for a go mod tidy ? after that I was able to run ~/lab/toto label list and it worked beautifully ty.

[prarit]

I like this change but I think it should be optional. @zampierilucas I think you should add a config option for this to enable the colors. That way users can set it in their lab.toml and not worry about it.

[zampierilucas]

@prarit I've updated my mr with you suggestion.