Add support for multiple urlPrefix when using /burp/report API

[tristanlatr]

It would be very useful to be able to report on a collection of urlPefix when using /burp/report API.

When having a very hight number of websites, this feature would be very valuable.

In the mean time, we can always start the burp-rest-api executable with options --headless=false --unpause-spider-and-scanner, start bunch of scans with the API, and generate the report manually from GUI by selecting everything.

If you think the implementation of such feature is not too complicated, I would try to mobilize my old Java skills and give it a go. But it's been a while!

Thanks for your feedback.

[ikkisoft]

Closing this one since I am consolidating all reporting enhancements in #125