add post-qa support for package data collection from arbitrary dirs

One of the decisions made in DM-6328 was that `validation_data_hsc` should not be cloned/installed by lsstsw due to its size. This will result in post-qa not capturing the EUPS product data (build_version, git_branch, etc.) for the test dataset. One way to address this this to add support to post-qa for collecting product data from arbitrary directories. Eg., {{ post-qa --product-dir ./validation_data_drp ...}}