Allow multiple paths in pathMapping

[mrgleba]

Is your feature request related to a problem? Please describe.
Right now in pathMapping one con provide only one path.
In our case sometimes one path serves files from multiple locations (we're doing a piece by piece transition from old code to new)
and there is no way to link both directories to the debugger

Describe the feature you'd like
Ideally pathMapping (and webRoot) should allow either a string or string array