meta: Add thunar

I used thunar for a while and it was a great experience with few
exceptions, however I will likely remove it in favor of a more command
line-based experience. Using thunar was a valuable learning exercise and
it helped me understand more about what file browsers actually do, and I
realized that I can replicate this experience fairly trivially while
giving me the benefits of my existing configuration.

thunar/.config/xfce4/helpers.rc

@@ -0,0 +1,2 @@
+TerminalEmulator=kitty
+TerminalEmulatorDismissed=true

thunar/README.md

@@ -0,0 +1,17 @@
+# thunar
+
+[thunar][thunar] is a GTK file manager.
+
+## Use Cases
+
+thunar can be used to:
+
+- Have a graphical interface for browsing files on a computer
+- Not worry about the cascading effect of nautilus
+- Have thumbnails update instantly, no refresh needed most of the time
+
+You should not use thunar if:
+
+- You want to search in your file browser (nautilus is better for this)
+
+[thunar]: https://gitlab.xfce.org/xfce/thunar