I have resurrected the original patch by Ranveer Aggarwal, which enables the user to hide the
color selector part of the docker.
There was one issue with the original: the docker settings button is inside the color selector, therefore when you hide
the selector, the only way to configure the docker is via the main menu, "Settings" -> "Configure Krita". To solve that I have added
a fallback settings button to the docker widget, which appears when the color selector part is hidden.