Mark Bakhit

This PR now has a functional `AsyncWhiteNoise` class. Will work on middleware, docs, and tests soon.

Django middleware is complete. Since this repo only supports Django 3.2+, I've converted the existing middleware to be async only.

@adamchainz `AsgiWhiteNoise` has been developed, and I've converted `WhiteNoiseMiddleware` to be async. I've confirmed via a local test environment that both work as expected. Before I begin rewriting the Django...

@strayer If you're interested, you can PR my branch with proper tests and documentation.

Did some more testing, looks like there's some funky behavior with the new Django middleware when `SecurityMiddleware` is above it. I will need to dig into this.

Fixed the issue around `SecurityMiddleware`. I am going to assume the current implementation is acceptable, unless told otherwise. I will begin fixing the tests soon.

This PR is now compatible with all existing tests. Adding more tests to cover the new ASGI stuff will come soon.

This PR is officially feature complete, fully tested, and fully documented. Since this PR is fairly bulky, the method to the madness is written within this PR's [original post](https://github.com/evansd/whitenoise/pull/359#issue-1125868994).

@evansd Given that I've had to read every file within this repo for the sake of this PR, I wouldn't mind helping out as a maintainer. That is, if you're...

Since I don't want to get into a cat-and-mouse game of constantly re-merging with main, hopefully this PR can get reviewed soon.