Add UI test cases for data formats

[kazuhitoyokoi]

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Proposed changes

I added UI test cases for "Working with data formats" in the cookbook website. At the same time, I updated XPath to the latest and made file structures the same as the cookbook website.

Checklist

• I have read the contribution guidelines
• For non-bugfix PRs, I have discussed this change on the mailing list/slack team.
• I have run grunt to verify the unit tests pass
• I have added suitable unit tests to cover the new/changed functionality

[coveralls]

Coverage increased (+0.03%) to 77.594% when pulling a53d0c0 on kazuhitoyokoi:master-adduitests into e3dab3c on node-red:master.

[kazuhitoyokoi]

Thank you!