[REQ] Update buildx integration to use new docker buildx dial-stdio

[cpuguy83]

What kind of request is this?

Improvement of existing experience

What is your request or suggestion?

In 3dec6b7 we added support for connecting to a buildx builder, with the limitation that it must either be a docker-container backed builder OR the default builder.
It also re-implements some things that buildx does internally for figuring what builder to connect to and making sure it is started up.
Some of this is relying on internal config files under ~/.docker/buildx` that aren't really documented and are just part of how buildx configures itself.

With buildx v0.13 we added support for a new command docker buildx dial-stdio.
This new command uses the stdin and stdout streams of the command as the transport for the buildkit client.
With this new command we no longer need to peek into the internal buildx config or manually bootstrap the builder instance.
We also get access to all the drivers that buildx supports.

I propose we remove the old logic and switch to this new command, with the caveat that it requires buildx 0.13.
Example usage: https://github.com/Azure/dalec/blob/3593addf5b0f57cc5ca6fc21705562fa545e93e8/cmd/localdev/main.go#L150-L170

Are you willing to submit PRs to contribute to this feature request?

• Yes, I am willing to implement it.