docker: Refactor Dockerfile process for official images (#32515)
Summary:
## Commit Message:
Refactors Dockerfile to be as parallel as possible with caching and adds a new Makefile to build said Dockerfile.
Also updated the README.md to reflect the changes as well as updated some of the verbage around running our latest Docker images.
Adds the new Dockerfile process to our CircleCI workflows
## How to build:
Building the new images is pretty simple, just requires `docker` > 18.06 since the new build process relies on `buildkit` caching and multi-stage build resolving.
### Development images
For `runtime` images:
```
make -f docker.Makefile runtime-image
```
For `devel` images:
```
make -f docker.Makefile devel-image
```
Builds are tagged as follows:
```bash
docker.io/${docker_user:-whoami}/pytorch:$(git describe --tags)-${image_type}
```
Example:
```
docker.io/seemethere/pytorch:v1.4.0a0-2225-g9eba97b61d-runtime
```
### Official images
Official images are the ones hosted on [`docker.io/pytorch/pytorch`](https://hub.docker.com/r/pytorch/pytorch)
To do official images builds you can simply add set the `BUILD_TYPE` variable to `official` and it will do the correct build without building the local binaries:
Example:
```
make -f docker.Makefile BUILD_TYPE=official runtime-image
```
## How to push:
Pushing is also super simple (And will automatically tag the right thing based off of the git tag):
```
make -f docker.Makefile runtime-push
make -f docker.Makefile devel-push
```
Signed-off-by: Eli Uriegas <eliuriegas@fb.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/32515
Differential Revision: D19558619
Pulled By: seemethere
fbshipit-source-id: a06b25cd39ae9890751a60f8f36739ad6ab9ac99
