Add back modifier keys to pointer events

[jamesnakagawa]

Is your feature request related to a problem? Please describe.

At my company, we are having an issue with using modifier keys like in the example given. The most common example is when the user cmd+tabs away from the window so that the window loses focus. In this case the keydown event is registered but not keyup, so when the user switches back to the window, the modifier key is still thought to be active. We also implemented a listener on window focus, but still ran into edge cases

Describe the solution you'd like

I would like if camera-controls handled modifier keys (alt, ctrl, and shift) in its pointer event handler similar to its previous behaviour.

Describe alternatives you've considered

Using keydown/keyup like in the example
Using window focus event in order to mitigate the downsides

Additional context

Thank you for this excellent library!
If I can offer to PR this change, I would be happy to.

[yomotsu]

Thanks for using camera-controls.

If I can offer to PR this change, I would be happy to.

PRs and issues are open to anyone. I would be happy to have PRs too.