Resolve Import hanging after completion

[mikejritter]

Resolves: https://jira.lyrasis.org/browse/FCREPO-3361

• Wrap BagVerifier using try-with-resources in order to close its resources

---

Testing

1. Start a fresh fedora repository, e.g. with fcrepo4-docker FEDORA_TAG=5.1.0 docker-compose up -d
2. Create a binary in the repository
3. Create a bag-config.yml for export

   bag-info.txt:
   Source-Organization: fcrepo-import-export
   Organization-Address: localhost
   External-Description: BagIt Bag

4. Run the exporter

   java -jar target/fcrepo-import-export-0.4.0-SNAPSHOT.jar --mode export --resource http://localhost:8080/fcrepo/rest --dir fcrepo-3361  --binaries --bag-profile beyondtherepository --bag-config bag-config.yml --user fedoraAdmin:secret3

5. Run the import and see the process no longer hang after completion

   java -jar target/fcrepo-import-export-0.4.0-SNAPSHOT.jar --mode import --resource http://localhost:8080/fcrepo/rest --dir fcrepo-3361  --binaries --bag-profile beyondtherepository --bag-config bag-config.yml --user fedoraAdmin:secret3