Dynamically add workers to an existing QSys object

[wlandau]

The resource requirements can ebb and flow over the course of running a drake workflow, especially for cases like ropensci/drake#1080 if there is a possibility of dynamic branching. Is it be possible to create new workers in an existing QSys object? If not, what is your opinion about such a feature?

w <- workers(2L)
w <- workers$launch_more_workers(4L)
# ...

cc @psadil

[mschubert]

It's not currently possible, but the worker API should (eventually) allow for it