Use system zsh plugins, remove redundant waybar network modules

- Source zsh-autosuggestions and zsh-syntax-highlighting from
  /usr/share/zsh/plugins/ instead of oh-my-zsh custom dir
- Add both as official packages
- Remove waybar network and custom/vpn modules (nm-applet covers this)
- Move tray from modules-left to first position in modules-right

defaults/xdg/waybar/style.css

@@ -42,7 +42,6 @@ window#waybar {
 #memory,
 #bluetooth,
 #temperature,
-#network,
 #pulseaudio,
 #tray,
 #mode,
@@ -59,7 +58,6 @@ window#waybar {
 #custom-gpu-usage,
 #custom-cpugov,
 #custom-dnd,
-#custom-vpn.connected,
 #power-profiles-daemon,
 #privacy,
 #gamemode,