Rebootless graphics switching

This changes out how the current graphics switching works, enabling
asusd to stop/start the display-manager to enable/disable PCI devices
and add/remove drivers as required.

All existing graphics modes and commands still work as normal.

G-Sync enable is now only through the bios setting, and on reboot
will set all relevant settings to Nvidia mode.

CHANGELOG.md

@@ -5,6 +5,18 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Added
+- GU502LU led-modes
+### Changed
+- Graphics switching is now rebootless, the daemon will now restart the
+  display-manager to switch modes instead. Caveats are:
+  + There is no confirmation from the daemon, the program issuing the command
+    must confirm the request.
+  + systemd only
+- Laptops with dedicated Nvidia mode:
+  + You still must reboot for the bios to switch modes
+  + On boot if dedicated mode is active then asusd will update the required configs
+    to put display-manager in nvidia mode
 
 # [3.0.0] - 2021-02-22
 ### Added