Keep Revit project open between tests

[Garrett-R]

RTF already has an awesome feature to keep Revit open between tests (--continuous).

It would be great to also keep the same Revit project open between tests that all rely on that project (i.e. have the same TestModel attribute).

[marchello2000]

FYI, this has been addressed with: https://github.com/upcodes/RevitTestFramework. Working on bringing these changes back to the main repo as well