maint: Update GoReleaser and CircleCI configs to publish multi-arch Docker image

[cdhunt]

This PR resolves a number of CircleCI Pipeline issues.

• Improve the filtering for the release job only on tag creation.
• Removes the dependency on integration-tests job from the release job. The flaky tests were frequently blocking the release.
  • Integration tests will now only run on PRs.
• Restores the Docker build/publish
  • Includes amd64, arm64, and i386 multi-arch manifest
• Uploads artifacts to CircleCI
• Fixes linting issues with README
• Add CircleCI Insights badge to README
• Uploads deb and rpm packages to CloudSmith
  • TODO: It looks like CloudSmith treats both format as duplicates and appends a -1 to the version.
  • TODO: Push the Docker images to CloudSmith as well (alternate to Docker Hub and their aggressive rate limits).
• TODO: The automated release notes regex patterns don't work for most of the commits. See releases/tag/v3.18.2-pre013

[tlimoncelli]

CC @cafferata

[cdhunt]

Test the multi-arch manifest:

docker run --rm -it stackexchange/dnscontrol:v3.18.2-pre013 version

[jauderho]

One item that is unclear to me is that it looks like GoReleaser is used to create the binaries but not the Docker images. Given that it can do both and that there is evidence this was the case at one point, is there a reason not to do so?

[cdhunt]

@jauderho It is building all artifacts including the docker images in this branch.

[tlimoncelli]

Wow! So much goodness in here!

[tlimoncelli]

(I'll let you do the merge)

[cdhunt]

@jauderho I guess more specifically, it is basically just invoking docker buildx build -f Dockerfile . We still need a Dockerfile and instaed rebuilding everything in the docker build I just copy in the binaries that gorelease spits out. I think Goreaser does some magic to put the version of dnscontrol matching the arch in the root of dist. I need to get a colleague to test on an M1 Mac.