Pull Dispatch with ds$ per VM from its description

[sei-jvessella]

Since the workspace document is visible to competitors, we should move the dispatches out of it in order to avoid potential information leakage. The place to move it is the description field for VMs because they don't have permission to view that field. We can't assume that the field will contain pure YAML, so there needs to be some parsing done in order to retrieve the dispatches.