[test-stress-options] improve coverage

* improve documentation
* reuse (create-test-data) for various regular transactions
* run (create-test-invoice-data) for business invoices
* fix max arguments which would crash for reports without options
* if report has start-date and end-date, insert valid dates to ensure
report runs on non-null book data.
* enable testing of previously disabled reports
* also dump book and invoices generated in populated book
* modify output to show full backtrace on error: In case of test
failure, previous would show a shortened exception name. Change to
display full backtrace, similar to crashing in live code. Uses
gnc:apply-with-error-handling existing API call.

Also clean up code.