Add support for NSSupportsAutomaticGraphicsSwitching

[marcoesters]

Description

Some MacBooks have two GPUs, a discrete and an integrated GPU. While the former is more powerful, it also consumes more power. By default, the discrete GPU is used.

To allow apps using OpenGL to use the integrated GPU and be more energy-efficient, the NSSupportsAutomaticGraphicsSwitching needs to be set to true.

menuinst currently does not support this flag - this PR adds this property to the schema.

Checklist - did you ...

• Add a file to the news directory (using the template) for the next release's release notes?
• Add / update necessary tests?
• Add / update outdated documentation?

[jaimergp]

Thanks! Can we add a link to the NS* keys documentation in line 180?
This will have to be added to the CEP schema, either via a new CEP or a small edit because the change is not too drastic.

[marcoesters]

Thanks! Can we add a link to the NS* keys documentation in line 180? This will have to be added to the CEP schema, either via a new CEP or a small edit because the change is not too drastic.

The NS* keys do not have a neat list like the CF* and LS* keys - or at least, I haven't been able to find them. In fact, some NS* keys are part of the CF*documentation (not this key though).