Support ACR as a buildx build driver

[rhuanbarreto]

What is the problem you're trying to solve
I wanted to simplify the usage of ACR Tasks by leveraging their buildx build drivers capabilities. There are some drivers available at https://docs.docker.com/build/builders/drivers/ and docker itself created their own driver to fuel their build cloud (docs)

Describe the solution you'd like
I wanted to be able to create/configure one driver that would run all docker build tasks into ACR tasks:

docker buidx create --driver="acr-tasks" builder-name

Then any docker build commands would be sent directly to ACR tasks without having to use the Azure CLI for sending it.

This would increase the interoperability of ACR tasks to be used as a target of docker build commands, which would reduce drastically the friction to adopt it. For example in build tools for monorepos there are plenty of already done integration with docker CLI but not the azure CLI