Add option to force 120hz when MacBook is on power saver mode

[alex20137]

On power saver mode, a MacBook gets forced to 60hz. Low power mode can offer significant energy savings through SoC changes alone. The only aspect that is actually felt is the sudden change in the refresh rate.

[waydabber]

I looked into this before but could not find a feasible way to fix this. This feature is not implemented like a normal VRR or mode-switch but is intertwined with power mode configuration and implemented at (near-)hardware level - this is mostly protected and the relevant APIs are private in a way that they cannot be invoked/accessed with apps created by third-parties. When power save mode is enabled, the system will still report and work as if 120Hz was max refresh rate (for example the UFO test thinks the display is running at 120Hz), it's just that the panel's controller seemingly does stuff differently.