maint: Update GoReleaser and CircleCI configs to publish multi-arch Docker image (#1682)

- 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](https://app.circleci.com/pipelines/github/StackExchange/dnscontrol/1285/workflows/b40ce89b-5a60-4ed2-874b-d47f383122b2/jobs/10051/artifacts) to CircleCI
- Fixes linting issues with README
- Add [CircleCI Insights badge](https://github.com/StackExchange/dnscontrol/tree/fix/cci#dnscontrol) to README
- Uploads deb and rpm packages to [CloudSmith](https://cloudsmith.io/~stackoverflow/repos/dnscontrol/packages/)
  - TODO: It looks like CloudSmith treats both formats 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](https://github.com/StackExchange/dnscontrol/releases/tag/v3.18.2-pre013)

Dockerfile

@@ -1,29 +1,13 @@
-FROM golang:1.19.0-alpine3.16@sha256:0eb08c89ab1b0c638a9fe2780f7ae3ab18f6ecda2c76b908e09eb8073912045d AS build
+# syntax = docker/dockerfile:1.4
 
-WORKDIR /go/src/github.com/StackExchange/dnscontrol
+FROM alpine:3.16.2@sha256:bc41182d7ef5ffc53a40b044e725193bc10142a1243f395ee852a8d9730fc2ad as RUN
 
-ARG BUILD_VERSION
+#RUN --mount=type=cache,target=/var/cache/apk \
+#    apk update \
+#    && apk add ca-certificates \
+#    && update-ca-certificates
 
-ENV GO111MODULE on
-
-COPY . .
-
-# build dnscontrol
-RUN apk update \
-    && apk add --no-cache ca-certificates curl gcc build-base git \
-    && update-ca-certificates \
-    && go build -v -trimpath -buildmode=pie -ldflags="-s -w -X main.SHA=${BUILD_VERSION}"
-
-# Validation check
-RUN cp dnscontrol /go/bin/dnscontrol
-RUN dnscontrol version
-
-# -----
-
-FROM alpine:3.16.2@sha256:bc41182d7ef5ffc53a40b044e725193bc10142a1243f395ee852a8d9730fc2ad
-
-COPY --from=build /etc/ssl/certs /etc/ssl/certs
-COPY --from=build /go/bin/dnscontrol /usr/local/bin
+COPY dnscontrol /usr/local/bin/
 
 WORKDIR /dns