feat: Add support for fido_dev_get_touch_{begin,status}

[codingllama]

Add support for touch polling operations. These are simpler to code against than fake assertions and clearer in their outcome. Additionally, they work with both U2F and FIDO2 keys seamlessly.

Example:

touch, err := dev.TouchBegin()
if err != nil {
	panic(err)
}
defer touch.Stop()

for {
	touched, err := touch.Status(maxWait)
	if err != nil {
		panic(err)
	}
	if touched {
		break // Done!
	}
}

[codingllama]

The API could go in many different ways, let me know if you have other ideas.

[codingllama]

Friendly ping @rosstimothy ?

[codingllama]

PTAL?