Upgrade wgpu (#676)

* Use the workaround from

gfx-rs/wgpu#1374 (comment)

* Upgrade to wgpu 0.9

We can't remove MPL from the deny.toml yes, as wgpu-subscriber
is still MPL

* swap to env-logger and log in all example paths

This also does let us remove MPL-2.0

As of #674, the crate of the
advisory is no longer in our tree

* Add a workaround for our *erm* strange codegen

Author: DJMcNab