esp-wifi: RFC Remove embedded-svc

[bjoernQ]

We optionally implement the wifi trait (and accompanying types) from embedded-svc - is that useful to someone or is it just unnecessary burden?

Is anyone actually using it (for non-esoteric reasons)?

[MabezDev]

From our meeting, we decided to remove support for now. We can always re-add it, but right now we don't see the value as not many crates (any?) build on top of these traits.