Adds conditionals to complaint detail body component for company resp…

[wwhorton]

…onse data

This PR adds some logic to only display the fields related to company response if that data is actually available. Otherwise, the heading and field isn't rendered.

Changes

• adds conditionals to ComplaintDetailBody component template

Testing

• yarn test
• Visit a complaint detail page without company response data, e.g. https://www.consumerfinance.gov/data-research/consumer-complaints/search/detail/5031625, and verify that none of the Company Response fields that lack data are displayed.

Checklist

• Changes are limited to a single goal (no scope creep)
• Code can be automatically merged (no conflicts)
• Code follows the standards laid out in the front end playbook
• Passes all existing automated tests
• New functions include new tests
• New functions are documented (with a description, list of inputs, and expected output)
• Placeholder code is flagged
• Visually tested in supported browsers and devices
• Project documentation has been updated (including the "Unreleased" section of the CHANGELOG)