Create and use Text Editor emblem
Many GNOME apps or libraries have an emblem, consisting of a symbolic icon on a background, that is used for their GitLab page (and Matrix room) which helps with their branding. It would be nice if Text Editor also uses this emblem style for its GitLab icon. See Initiatives#36 for more info.
Below are some examples of how an emblem could look like. When in use, they will be circular or have rounded corners.