Dynamic-pin / type-erased pin type

[ryankurte]

hey there,

i've recently been working with the ATSAMD51 devices and over there they've provided a DynPin type that alleviates pin-type constraints, which is super helpful for projects that run on different hardware variants both at compile or runtime.

not sure this is the right place to put this but, as it applies to all the stm32XXX-hal crates, would this be something y'all are interested in adding?

[adamgreig]

I've moved this to the meta repo which is meant to be a good location for this sort of issue, though I'm not sure how many of the HAL maintainers are subscribed... you might also get some good discussion in the stm32-rs channel or opening issues on some specific HALs.

Sounds like a good idea to me to have a totally erased type, in addition to the current partially erased by port ones.