Proposal for in-progress job listing

[jbaublitz]

I proposed in stand up today adding a new command to list in progress jobs, particularly in the case of something like online re-encryption where it can take a long time and is prone to lasting longer than the default D-Bus timeout in stratis-cli.

As a result, I would like to propose tracking tasks that are spawned in threads so that we can have a command to list in progress operations. This would be accomplished at the threading layer, above locking, so theoretically it should always be visible which tasks are in progress. My assumption is that there should be some helper methods in tokio in terms of tasks spawning that could be useful here. We may be able to have minimal changes and accomplish what we want by running code on task start and task end, updating a synchronized data structure with the information about the jobs that are in progress.

[jbaublitz]

Unless we plan to incorporate something like this into #3938 I believe we can close this out for now. It seems that we've come to a solution that does not require task tracking.