Create Github Action/Workflow to promote versions between environments.

[dsiguero]

• From dev (to QA)
  This one is a bit tricky, because we probably shouldn't rely on the latest pointer, as there might be new versions created in the relevant repo, that haven't been deployed yet. Maybe checking tags in AWS/creating SSM parameters with the versions. Although maybe it doesn't matter because it's QA?
• From QA (to Prod)
  Here it should be more straightforward, given that QA will have actual "named" versions (vX.Y.Z) and it should be a matter of replacing env.json