Refactor GPU detection functions and tooltip

Removed the DetectRenderGPU function and updated BuildGpuTooltip to only summarize the display GPU.

Author: Tiflit

src/gpu/gpu_detection.h

@@ -7,16 +7,9 @@
 // Returns true on success and fills outState.
 bool DetectDisplayGPU(GpuState& outState);
 
-// Detects the GPU used for rendering by creating a D3D11 device.
-// Returns true on success and fills outState.
-bool DetectRenderGPU(GpuState& outState);
-
 // Creates a dummy D3D11 device to wake/activate the dGPU.
 // Returns true on success.
 bool ActivateRenderGPU();
 
-// Builds a tooltip string summarizing display + render GPUs.
-std::wstring BuildGpuTooltip(
-    const GpuState& display,
-    const GpuState& render
-);
+// Builds a tooltip string summarizing the display GPU only.
+std::wstring BuildGpuTooltip(const GpuState& display);