Allow the ability to edit container labels for preview deployments

[qverkk]

Hey,

So basically right now it's hard to test preview deployments if you require to change some additional container labels to enable/change some features within the dynamic traefik configuration. This feature would allow you to deploy the preview deployment with some default container labels, but once it's deployed, you would be able to change them to test the configuration that would be later deployed to prod

Best regards