Add ability to build portable case from an existing portable case

The portable case is commonly used as the "working copy" for investigators to review the data for evidence within scope of the warrant. Being able to create a portable case featuring only the tagged evidence (within scope of the warrant) from an existing portable case would be a very powerful tool. Going back to the examiner with a portable case containing the tagged evidence and asking them to upload the portable case into the parent case (to then make a new portable case containing the tagged evidence) is not a practical solution. The PC format is such a powerful tool for attorneys and other key partners to review data; it doesn't compare to the export/report (PDF, HTML, Excel) tools currently available within the PC.