xsession: add option xsession.initBeforeSystemd

This commit add an option called xsession.initBeforeSystemd to setup
xsession related options such as merging xresources and doing other
x11 related setup before hm-graphical-session.target is started.

For example, before this commit, if we set dpi using xresources, it
won't work for user graphical systemd services since xresources is
merged after hm-graphical-session.target is started.

modules/config/home-cursor.nix

@@ -139,7 +139,7 @@ in {
     }
 
     (mkIf cfg.x11.enable {
-      xsession.initExtra = ''
+      xsession.initBeforeSystemd = ''
         ${pkgs.xorg.xsetroot}/bin/xsetroot -xcf ${cursorPath} ${
           toString cfg.size
         }

modules/xresources.nix

@@ -99,6 +99,6 @@ in {
         '';
       };
 
-      xsession.initExtra = xrdbMerge;
+      xsession.initBeforeSystemd = xrdbMerge;
     };
 }

modules/xsession.nix

@@ -70,6 +70,13 @@ in {
         description = "Extra shell commands to run before session start.";
       };
 
+      initBeforeSystemd = mkOption {
+        type = types.lines;
+        default = "";
+        description =
+          "Shell commands to run before starting hm-graphical-session.target. For example, configuring x11 cursor and dpi.";
+      };
+
       initExtra = mkOption {
         type = types.lines;
         default = "";
@@ -200,6 +207,8 @@ in {
         fi
         unset HM_XPROFILE_SOURCED
 
+        ${cfg.initBeforeSystemd}
+
         systemctl --user start hm-graphical-session.target
 
         ${cfg.initExtra}

tests/modules/misc/xsession/basic-xsession-expected.txt

@@ -3,6 +3,8 @@ if [ -z "$HM_XPROFILE_SOURCED" ]; then
 fi
 unset HM_XPROFILE_SOURCED
 
+
+
 systemctl --user start hm-graphical-session.target
 
 init extra commands