Add Discrete key
Reworked in !69
Implements #39
Some notes:
- amdgpu implementation relies on libdrm_amdgpu
- Checks for a discrete GPU the same way as Mesa
- Nouveau implement queries the device through libdrm to get the relevant platform
- In this PR the proprietary Nvidia Drivers are hardcoded as discrete, in the future a proper implementation could be made.
- No Intel implementation at the moment
- libdrm_i915 does not appear to have any logic for querying Xe GPUs yet
- Mesa implements support for this, but statically vendors all of the code, not feasible to copy without a lot of extra code.
- Intel has a publicly available list of hardware ID's, a list could be made with all known discrete GPUs https://dgpu-docs.intel.com/devices/hardware-table.html