[Client] user should not be able to add/delete ports beyond port minimum/maximum

[jacobdgm]

In the "WorkflowJob Ports" dialog, there are "Min" and "Max" values for each of the input and output port types. Currently, if you already have one instance of a given input port with a Max of 1, Rodan Client allows you to add additional instances of the port. Similarly, it allows you to delete ports of a given type even if you are already at the minimum.

Ideally, the "Add"/"Delete" buttons would be greyed out if adding/deleting instances of the port would exceed a minimum/maximum.