[PATCH v4 0/2] MR2120: user32: Post WM_INPUT_DEVICE_CHANGE when registering for notifications

[Evan Tang (＠etang-cw)]

This seems to be relied on by some versions of [this Unreal Engine input plugin](https://www.unrealengine.com/marketplace/en-US/product/wm-input-manager)

Note: I'm not sure how to deal with `HID_USAGE_GENERIC_KEYPAD`, which (I think) would fall under `RIM_TYPEKEYBOARD`.  Do we need to store extra info to differentiate these from `HID_USAGE_GENERIC_KEYBOARD` or is there something in the device info struct that can differentiate them?

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  v4: user32: Post WM_INPUT_DEVICE_CHANGE when registering for notifications
      user32: Add tests for WM_INPUT_DEVICE_CHANGE messages

https://gitlab.winehq.org/wine/wine/-/merge_requests/2120