Add Options::input_options for click-delay etc

[girtsf]

This takes 3 hardcoded constants from input_state.rs and puts them in a InputOptions struct that then gets added to Options. This allows adjusting these values at runtime, for example, to increase MAX_CLICK_DIST for touchscreen usage.

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[girtsf]

Background on the PR: I'm working on a UI for a touchscreen device and I've found that the default MAX_CLICK_DIST of 6 pixels doesn't work well - most finger taps will "slide" on the screen more than 6 pixels and thus won't register as clicks. Setting the value to a higher number makes the interface less finicky.

Thoughts on this? I don't quite like that I had to stash InputOptions in PointerState and InputState so that functions such as wants_repaint_after and is_long_press can do their calculations. Better ideas? Or is this acceptable?

(Maybe outside the scope of this PR, but maybe we could consider separate config values for mouse vs touch? The latter is much less precise. From a quick glance, this would require changing some of the plumbing that translates touch events into PointerButton events.)

[emilk]

I like this approach better than the alternative in #4986

[emilk]

We should note here that this is copied from egui::Options at the start of each frame, and is only here for convenience

[girtsf]

Done. Let me know if you think Arc would be a better solution here. Currently it's just a couple of floats, so performance wise it might be a wash between Arc and copying the floats.