Add Discrete GPU Detection

supersedes !68 (closed) since it has become messy and unclear.

This Merge Request adds a boolean Discrete key which signifies if the GPU in question is considered Discrete or not by querying the driver and heuristics.

Detection is done in the following ways through udev:

• amdgpu
  • device info is queried
  • if AMDGPU_IDS_FLAGS_FUSION is set, its an APU
• nouveau
  • device info is queried
  • if the device platform is IGP or SOC its not discrete
  • otherwise its considered discrete
    • while this could be considered wrong, there are few available integrated Nvidia GPUs and to my knowledge no Multi GPU systems with an integrated Nvidia GPU
• nvidia
  • always considered discrete
    • I found no good way to query the proprietary nvidia drivers without having to poke at it with proprietary libraries.
    • the same reason as for why the nouveau detection consideres anything else discrete also applies
• i915
  • the PCI ID of integrated Intel GPUs appears to always be `0000:00:02.0`
    • I've asked around the community for sample data and out of 17 sets of data it applied every time

I've personally tested this against the following setups:

• Intel integrated GPU
• Nvidia discrete GPU (both using Nouveau and Nvidia drivers)
• AMD discrete GPU
• AMD integrated GPU

and this far had no issues.

CI failure appears to be unrelated to any code issues

it compiles fine locally and on copr