Create and use Evince emblem on GitLab and Matrix
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 Evince also uses this emblem style on both platforms. See Initiatives#36 for more info.
Below are some examples of how an emblem could look like. The first one is generated with Emblem. The second one is generated manually and differs slightly from other emblem designs, but I included it because it looks better to me in this case. Their color is the same as the one in the regular icon. When in use, the emblem will be circular or have rounded corners.