Add a new field.

To add a new field, a section must first be created.

1. Adding a section
   Set the type to "section" and provide the formId and sectionHeading.
2. Adding a field
   Provide the formId, label, and sectionId, and set the type should be set to one of the following field types:
   • address
   • checkbox
   • currency
   • datetime
   • email
   • file
   • id
   • name
   • number
   • phone
   • radio
   • richtext
   • select
   • text
   • textarea