refactor: move task skill integration up the stack

[th3james]

Changes

Moves integrations with VS Code task creature up to the imperative shell, keeps command creation as function core
https://www.destroyallsoftware.com/screencasts/catalog/functional-core-imperative-shell

• Makes NpxSkills and TopoSkill's command creation methods return values rather than actually creating the task
• Moves the creation and running of the task up to the action at the top of the stack
• Reduces some of the ceremony of setting up accurate test values in tests where the implementations which consume them are mocked, because these are extra lines of code which bring zero additional verification

Screenshots