utils: add `include_shared_workflows` parameter

[DaanRosendal]

Adds new include_shared_workflows parameter to optionally retrieve unowned workflows that are shared with the user.

Closes reanahub/reana-client#687

[giuseppe-steduto]

These are very valid concerns that indeed require a better discussion.

Option 1: I was trying to put myself in the shoes of other users, and while it may make commands appear less intuitive, it essentially boils down to obtaining the UUID from the list command. Although this might seem like a minor inconvenience, I think this could be quickly become moderately annoying to users if the workflow has to be interacted with a lot.

Option 2: I haven't really explored the possibility, but maybe a way to make fewer changes to the code is to enable a fully-qualified name made like email/my-analysis.1.2, but default to the user's workflow when only the workflow name is given. In this way, my-roofit-analysis, my-roofit-analysis.1, and my-roofit-analysis.1.12 would still work as they are right now, but user@example.com/my-roofit-analysis.1 for example would refer to the workflow owned by user@example.com with that same name and major run number, but biggest minor run number (or error if it does not exist). In this way, there wouldn't be ambiguity.

Further discussion within the team is in any case needed to weigh the pros and cons of these options well.

[mdonadoni]

Included in https://github.com/reanahub/reana-db/pull/216, the discussion can continue there