New reports in new exports can now import

MSP-9783

* Extracted import_report from monstrous import_msf_collateral;
simplified and clarified approach
* Updated report_report: includes all attrs provided vs subset, provides
more helpful error message
* Added report_artifact: adds child artifact for reports, handles
various troublesome cases
* Tested on all report types with a legion of option variants
Land #3269 (Pro) fix report import issue