FCREPO-3812: Add failure only reporting option

[mikejritter]

JIRA Ticket: https://fedora-repository.atlassian.net/browse/FCREPO-3812

What does this Pull Request do?

• Add flag for reporting only failed validations
• Update logic to account for failed only flag

What's new?

Updates the FileSystemValidationResultWriter to be able to write out only failed validations.

How should this be tested?

• Migrate some data
• Run the validator with the --failure-only flag, e.g.

  java -jar target/fcrepo-migration-validator-1.2.0-SNAPSHOT-driver.jar -c /data/migration/f6-migration/data/ocfl-root -d /data/migration/f3dataset/datastreams -o /data/migration/f3dataset/objects -s legacy -r /data/migration/report --failure-only
  

• Check the resulting files only contain validations which failed, some something like grep -R OK json/ should return no matches.

Additional Notes:

• This is a little awkward when there are no errors as you're left with either and empty csv file or a mostly blank HTML report. I could disable that portion of the report gen as well if there are no errors, or generate something for this condition.
• Likewise, there weren't any tests covering report generation, so I haven't added any. This could be done before merging if desired.

Interested parties

@fcrepo/committers

[dbernstein]

Excellent @mikejritter. Yes, please ensure there is some feedback to the user when in errors only mode and there are not errors. Also yes please add some tests to cover report generation. Maybe at a minimum some smoke tests confirming the cases of

1. all okay for html and csv
   2)errors only flag = true for csv and html for validation with no errors.

[mikejritter]

@dbernstein I made a few small changes to the template to make it more clear that these are object reports. I think that's sufficient (at least for now) for running in --failure-only mode.

I also added an integration test which runs the report generator for both HTML and CSV reports. It's only checking that the expected object reports exist, we could go further and check validations but I left that out for now.