New package: docker-buildx-0.7.1

[gbrlsnchs]

I had to use this command at work and it simply didn't exist. I had previously used it on Arch and didn't really know why it wasn't available on Void as well.

It happens that this command is a Docker CLI plugin, and comes bundled with Docker when distributed via DEBs or RPMs, but Arch also packages it along with their Docker package.

In my opinion, it makes more sense to package this just like Docker Compose (which since v2 is also a Docker CLI plugin), that is, as a separate package, easy to install, and which will work out of the box once installed.

P.S.: I based this template off docker-compose's.

Testing the changes

• I tested the changes in this PR: YES

New package

• This new package conforms to the quality requirements: YES

Local build testing

• I built this PR locally for my native architecture, (x86_64, both for glibc and musl)
• I built this PR locally for these architectures (if supported. mark crossbuilds):
  • aarch64-musl
  • armv7l
  • armv6l-musl

[gbrlsnchs]

@paper42 Rebased in order to squash files. That means commits I linked to you won't work anymore, but patches still apply. 🙂

Thanks for your review!