Add an option to retry a failed cachix deploy deployment from the workspace dashboard

[Kranzes]

Sometimes deployments fail for unexpected reasons such as lack of storage available on the boot partition and the only way to fix it is to manually login to the machine and "take care of it". Once you make some space for the new deployment, you don't want to always deploy to all of the agents like in CI. You may want to only retry the failed deployments, having a button for that on the dashboard can be very handy.