Related #2256

Occasionally a workspace enters an undeletable state because the underlying resources are already deleted or are otherwise inaccessible.

For example, in my test deployment my Docker volumes reset overnight, but since Coder no longer delete the volume, I cannot delete my workspace. In another case Coder lost access to a cloud account so I had to delete the workspace resources directly.

I propose we add a workspace force delete functionality that deletes the state even if provisioner delete fails. We should restrict this functionality to Template Admins so regular users can't create resource sprawl.