Added support for the flag /directory to search for assembly dependencie...

Added support for the flag /directory to search for assembly dependencies in the given directory. Related to SONARFXCOP-9.

These changes need to be applied together with the changes on the c-sharp plugin (I also created a pull request for these changes) https://github.com/kashingl/sonar-csharp/commit/117442ea61a1f2f7c60cd9673652608fd9ea2b85