Review `DelayUs/DelayMs` API and possible migrate away.

[jordens]

https://github.com/quartiq/stabilizer/pull/590#pullrequestreview-1066610618

We should try to get away from DelayUs/DelayMs at some point in the future. The API is an invitation for error: Into<u32> strips units, granularity, and context as delay_us(something.into()) looks just as good (but is wrong) if something.into::<u32>() are actually ms. It does seem like we should leverage as much as possible from fugit.