Feature: Personal limits per sub-tasks

[stepev]

There is a typical Jira board design where requirements, i.e. "features", are managed on the board. At the same time, to manage a more detailed list of what needs to be done to complete these features, developers use subtasks for these features. In this way, to indicate who is doing what part of the feature, developers assign subtasks to themselves.

In such an approach, because multiple developers can be working on the same feature, counting personal WIP by feature is useless.

Describe the solution you'd like to see.
It would be useful to have the option to count personal WIP and WIP limits against subtasks rather than parent tasks. Parent task shouldn't be counted at all.

Parent tasks without subtasks are a special case. I think that these should be accounted for in the personal WIP.

So personal WIP = "number of subtasks the person is assigned to" + "current parent tasks without subtasks the person is assigned to".