Support arbitrary metadata on workloads

[autodidaddict]

Proposed change

When deploying a workload, allow for the deployment request to contain an arbitrary set of metadata (key->value string map). This set of metadata would be discoverable when getting node or workload information.

Use case

When someone is working with large numbers of workloads, it might get difficult to correlate workloads with the request that deployed it. With this type of metadata available on the workload, such correlation would be relatively easy. In short, this has almost the same purpose as the "tags" feature does on nodes.

Contribution

No response