Add application icons

I have created an icon for the application! Since the name "Damask" is fabric-related, I chose a loom as the icon metaphor. I have also created a badge for the project with Emblem, using the new symbolic icon. You can download it and set it as the project image here on GitLab, it's a trend among many GNOME projects right now 😄

I have put the icons in their proper places (/data/icons/hicolor), along with the source file in the /data directory. You might have to make some changes in other places to make the application actually use them, I'm not familiar with that.

Icon type	Preview
Primary
Devel
Symbolic
Badge

If there are any changes you want made to the icon, please let me know.