hyprland: Replace $mainMod with SUPER

I don't think I've ever had to change from SUPER in my years of using
Linux, and if I ever had to, it'd be a simple find and replace.

Using SUPER explicitly here makes things easier to read and understand
without having to worry about additional variables.

hyprland/.config/hypr/hyprland.conf

@@ -116,54 +116,50 @@ device:epic-mouse-v1 {
 # windowrulev2 = float,class:^(kitty)$,title:^(kitty)$
 # See https://wiki.hyprland.org/Configuring/Window-Rules/ for more
 
-
-# See https://wiki.hyprland.org/Configuring/Keywords/ for more
-$mainMod = SUPER
-
 # Example binds, see https://wiki.hyprland.org/Configuring/Binds/ for more
-bind = $mainMod, Return, exec, kitty --single-instance
-bind = $mainMod, Q, killactive,
-bind = $mainMod, P, exec, grimblast copy area
-bind = $mainMod, escape, exit,
-bind = $mainMod, V, togglefloating,
-bind = $mainMod, R, exec, wofi --show drun
-bind = $mainMod, B, pseudo, # dwindle
-bind = $mainMod, J, togglesplit, # dwindle
+bind = SUPER, Return, exec, kitty --single-instance
+bind = SUPER, Q, killactive,
+bind = SUPER, P, exec, grimblast copy area
+bind = SUPER, escape, exit,
+bind = SUPER, V, togglefloating,
+bind = SUPER, R, exec, wofi --show drun
+bind = SUPER, B, pseudo, # dwindle
+bind = SUPER, J, togglesplit, # dwindle
 
 # Move focus with mainMod + hjkl
-bind = $mainMod, H, movefocus, l
-bind = $mainMod, L, movefocus, r
-bind = $mainMod, K, movefocus, u
-bind = $mainMod, J, movefocus, d
+bind = SUPER, H, movefocus, l
+bind = SUPER, L, movefocus, r
+bind = SUPER, K, movefocus, u
+bind = SUPER, J, movefocus, d
 
 # Switch workspaces with mainMod + [0-9]
-bind = $mainMod, 1, workspace, 1
-bind = $mainMod, 2, workspace, 2
-bind = $mainMod, 3, workspace, 3
-bind = $mainMod, 4, workspace, 4
-bind = $mainMod, 5, workspace, 5
-bind = $mainMod, 6, workspace, 6
-bind = $mainMod, 7, workspace, 7
-bind = $mainMod, 8, workspace, 8
-bind = $mainMod, 9, workspace, 9
-bind = $mainMod, 0, workspace, 10
+bind = SUPER, 1, workspace, 1
+bind = SUPER, 2, workspace, 2
+bind = SUPER, 3, workspace, 3
+bind = SUPER, 4, workspace, 4
+bind = SUPER, 5, workspace, 5
+bind = SUPER, 6, workspace, 6
+bind = SUPER, 7, workspace, 7
+bind = SUPER, 8, workspace, 8
+bind = SUPER, 9, workspace, 9
+bind = SUPER, 0, workspace, 10
 
 # Move active window to a workspace with mainMod + SHIFT + [0-9]
-bind = $mainMod SHIFT, 1, movetoworkspace, 1
-bind = $mainMod SHIFT, 2, movetoworkspace, 2
-bind = $mainMod SHIFT, 3, movetoworkspace, 3
-bind = $mainMod SHIFT, 4, movetoworkspace, 4
-bind = $mainMod SHIFT, 5, movetoworkspace, 5
-bind = $mainMod SHIFT, 6, movetoworkspace, 6
-bind = $mainMod SHIFT, 7, movetoworkspace, 7
-bind = $mainMod SHIFT, 8, movetoworkspace, 8
-bind = $mainMod SHIFT, 9, movetoworkspace, 9
-bind = $mainMod SHIFT, 0, movetoworkspace, 10
+bind = SUPER_SHIFT, 1, movetoworkspace, 1
+bind = SUPER_SHIFT, 2, movetoworkspace, 2
+bind = SUPER_SHIFT, 3, movetoworkspace, 3
+bind = SUPER_SHIFT, 4, movetoworkspace, 4
+bind = SUPER_SHIFT, 5, movetoworkspace, 5
+bind = SUPER_SHIFT, 6, movetoworkspace, 6
+bind = SUPER_SHIFT, 7, movetoworkspace, 7
+bind = SUPER_SHIFT, 8, movetoworkspace, 8
+bind = SUPER_SHIFT, 9, movetoworkspace, 9
+bind = SUPER_SHIFT, 0, movetoworkspace, 10
 
 # Scroll through existing workspaces with mainMod + scroll
-bind = $mainMod, mouse_down, workspace, e+1
-bind = $mainMod, mouse_up, workspace, e-1
+bind = SUPER, mouse_down, workspace, e+1
+bind = SUPER, mouse_up, workspace, e-1
 
 # Move/resize windows with mainMod + LMB/RMB and dragging
-bindm = $mainMod, mouse:272, movewindow
-bindm = $mainMod, mouse:273, resizewindow
+bindm = SUPER, mouse:272, movewindow
+bindm = SUPER, mouse:273, resizewindow