Add option to run command before UI is initialised (closes #798)

Signed-off-by: AnErrupTion <anerruption@disroot.org>

src/config/Lang.zig

@@ -51,6 +51,7 @@ err_perm_group: []const u8 = "failed to downgrade group permissions",
 err_perm_user: []const u8 = "failed to downgrade user permissions",
 err_pwnam: []const u8 = "failed to get user info",
 err_sleep: []const u8 = "failed to execute sleep command",
+err_start: []const u8 = "failed to execute start command",
 err_battery: []const u8 = "failed to load battery status",
 err_switch_tty: []const u8 = "failed to switch tty",
 err_tty_ctrl: []const u8 = "tty control transfer failed",