[UX] - Customization of keys in labeling page

[lumburovskalina]

What would you improve?
On the project settings page we can customize which key can be used for which label. As an improvement we can add the customization of the labels on the labeling page too, so the user doesn't need to go to the settings page to set the labels. With the current implementation, the user can add labels on the labeling page but adding the keys there too would improve the usability.