X11: Move pieces from i3 and zshenv into xinitrc

Move everything that is desirable independent of the WM or shell into
xinitrc.
Move .Xresources and .Xmodmap into .config/X11.
Remove all unneeded GNOME bits from i3 config.
Make compositor launch script portable.
Add locker symlink and launch.sh similar to the compositor.

meta/install.conf.yaml

@@ -20,10 +20,6 @@
       stdout: true
       stderr: true
 - link:
-    ~/.Xmodmap:
-        path: .Xmodmap
-    ~/.Xresources:
-        path: .Xresources
     ~/.xinitrc:
         path: .xinitrc
     ~/.zshenv: