[DT-936] Ensure H3 validation fields have correct styling

[fboulnois]

Addresses

https://broadworkbench.atlassian.net/browse/DT-936

Summary

Previously, form fields that were used at the H3 level inherited the default form field styling which lead to inconsistencies in the DAR form styling. I added an optional titleStyle field that will allow a developer to set any styling on the title part of the form field so it can match the rest of the styling of the page. This leads to a consistent looking DAR page:

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[rushtong]

Thank you! 👍🏽