launch.json: Allow to specify process name filter in command:pickProcess OR present picker when using processName property when there is more than one process

As a user, who wants to a process named `foo` but there is more than one process with this name, I'd like to attach to it without having to type the process name in the filter presented by `${command:pickProcess}`. Essentially, I want an option to pre-populate the filter.
An alternative would be to improve the `processName` property to not give an error to the user if there is more than one process but rather present a picker with the list of processes of that time.

Background: When debugging binary PowerShell modules (i.e. written in .Net). there is usually more than one PowerShell process running.