feat(automation): onboard automation templates list datasource

[SerseusWasTaken]

Description

Relates to STACKITTPR-790

Checklist

• Issue was linked above
• Code format was applied: make fmt
• Examples were added / adjusted (see examples/ directory)
• Docs are up-to-date: make generate-docs (will be checked by CI)
• Unit tests got implemented or updated
• Acceptance tests got implemented or updated (see e.g. here)
• Unit tests are passing: make test (will be checked by CI)
• No linter issues: make lint (will be checked by CI)

[cgoetz-inovex]

these 2 tests are a bit contradictory. From paginate.All:

	var items []Item
	for item, err := range Items(request, opts...) {
		if err != nil {
			return items, err
		}
		items = append(items, item)
	}
	return items, nil

So an empty, non-nil list would never be returned.

I'd suggest to change the implementation to accept nil slices. From a glance it looks like this would be safe. slices.SortFunc does not panic on a nil slice.