Enable test-runner to accept a list of tags to identify
which test groups the user wishes to run.
Also allow test-runner to perform multiple iterations
of a test run.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: John Wren Kennedy <john.kennedy@delphix.com> Reviewed-by: George Melikov <mail@gmelikov.ru> Signed-off-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Closes #6788