Same as #541, with some refactoring.
cc @chtheis @sc68cal
Make the second WithWorkspace function (without the IEnumerable) work…
… like the first (with the IEnumerable) with the Janitor
Don't share workspaces with different mappings.
Merge the two WithWorkspace methods.
`GetWorkspace` is more of `CreateWorkspace`.
Update release notes.
Make the diff easier to read.