Use async embedded-hal

[newAM]

This is not complete, but it does compile. I am not going to be actively working on it (not for a few months anyway). I wanted to share an up-to-date version since #175 is out of date, and also no longer being worked on.

Things to fix:

1. waiting for the busy pin could be implemented better.
2. examples do not compile, linux-embedded-hal does not implement async
3. synchronous support

Anyone please feel free to use any commits here in other pull-requests.

[vhdirk]

Did you see this one? https://github.com/vhdirk/epd-waveshare-async

Edit: I didn't read the post with much attention. I've updated https://github.com/caemor/epd-waveshare/pull/175 to embedded hal 1.0 and rebased on epd-waveshare main