use image containing installer deps for fleetdm/fleetctl

[roperzh]

This changes our workflows to build and push the Docker image defined at tools/fleetctl-docker/Dockerfile as part of the release process. (#6682)

Checklist for submitter

If some of the following don't apply, delete the relevant line.

• [x] Manual QA for all new/changed functionality

[roperzh]

Does .goreleaser.yml work out of the box?

kind of, yeah! it's used by a workflow:

https://github.com/fleetdm/fleet/blob/966bfbf85e1eec62d80fa69e1b1a43a02389d658/.github/workflows/goreleaser-fleet.yaml#L40-L45

There's also another workflow that publishes snapshots, seems like it currently builds the docker image, but it only publishes fleetct/fleet to Docker Hub, we could publish fleetdm/fleetctl on every PR too if we think it's useful (maybe for testing on CI?)

https://github.com/fleetdm/fleet/blob/966bfbf85e1eec62d80fa69e1b1a43a02389d658/.github/workflows/goreleaser-snapshot-fleet.yaml#L47-L49

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I also went back and added the workflow to manually publish the image again, since we're not publishing the image on every push it might be useful to have it around for testing, what do you think?

[lucasmrod]

I also went back and added the workflow to manually publish the image again, since we're not publishing the image on every push it might be useful to have it around for testing, what do you think?

Yes, let's keep that around.

[lucasmrod]

There's also another workflow that publishes snapshots, seems like it currently builds the docker image, but it only publishes fleetct/fleet to Docker Hub, we could publish fleetdm/fleetctl on every PR too if we think it's useful (maybe for testing on CI?)

If the images are not big (~50MB like fleet) then maybe we should just do it on every PR.

[roperzh]

@lucasmrod CI is passing now and I think this is ready for another review 🙏