CLI: alias tweaks

[josephjclark]

Small things to tidy really soon

• When fetching a sandbox, automatically set the alias (unless provided)
• Write the alias to openfn.yaml (otherwise it's a bit hard to work out the current local alias)

Also likely related: we need to work out what to do if there are multiple local projects with the same UUID. The full alias should be unique, so that's all we need. If there are multiple local matches with the same UUID, we just pick by the matching alias. We should be more robust here.

To repro: fetch with a custom path -o out.yaml. That duplicates your uuid locally which stops checkout working (needlessly - we should always know the local project file we're tracking_)

Also, maybe ensure that config is the first key in openfn.yaml, with project second (because the forked_from map might get big)