cmd: add new image-builder binary and initial `list-distros` #3069

	# This workflow runs on PRs and the merge queue and is responsible for starting
	# the "Start GitLab CI" workflow in a way that makes it possible to use
	# secrets. The workflow first runs source preparation to make sure that the
	# gitlab-ci.yml is up to date.
	---
	name: GitLab

	on: # yamllint disable-line rule:truthy
	pull_request:
	branches:
	- "*"
	# for merge queue
	merge_group:

	jobs:
	prepare:
	name: "🔍 Check source preparation"
	runs-on: ubuntu-latest
	steps:

	- name: Set up Go 1.21
	uses: actions/setup-go@v5
	with:
	go-version: "1.21"
	id: go

	- name: Check out code into the Go module directory
	uses: actions/checkout@v4
	with:
	ref: ${{ github.event.pull_request.head.sha }}

	- name: Install dependencies
	run: \|
	sudo apt update
	sudo apt install -y libgpgme-dev libbtrfs-dev libdevmapper-dev

	- name: Check that source has been prepared
	run: \|
	./tools/prepare-source.sh
	if [ -n "$(git status --porcelain)" ]; then
	echo
	echo "Please include these changes in your branch: "
	git status -vv
	exit "1"
	else
	exit "0"
	fi

	gitlab-ci-helper:
	name: "Gitlab CI trigger helper"
	runs-on: ubuntu-latest
	steps:
	- name: Trigger
	run: echo "GitLab trigger complete"

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