EVHZ Fork/Better polling verification tool

[geefr]

Docs on evhz-usage page could be improved regardless

evhz itself is kinda awkward to deal with - Would be better to have some tool that

• lets user select one device to test, instead of all at once (i.e moving the mouse while testing the pad won't flood terminal with spam)
• lets user select an input driver - Testing through X11 is cool, but being able to verify through SDL/Other input tech would be useful too
• Gives better feedback on what to do for testing, and whether things are correct - Should just be a big green tick/similar if things work, rather than needing users to sift through terminal logs for a vague '100Hz' marker and call that working