Retain extracted, unjoined table output when joining data in CytoTable

@jenna-tomkinson brought up an idea for an enhancement that involves providing both the extracted unjoined table data and the joined table data as part of CytoTable output. At the moment, when `join=True`, the initially extracted data is removed as a kind of "cleanup" step. Jenna mentioned it would be helpful to have access to the unjoined data in addition to the joined data.