Add InputDeviceIconSetSO configuration guide and related documentation

- Created a new markdown file detailing the configuration of InputDeviceIconSetSO.
- Included sections on system architecture, field explanations, image specifications, and complete workflow from setup to runtime.
- Documented the automatic device recognition logic and provided troubleshooting for common issues.
- Added references to relevant files and scripts for easier navigation.

Assets/_Game/Scripts/Editor/Input/InputIconStudioWindow.cs.meta

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