Feature Request: Allow Anchors to serve content without forms

[JakeUrban]

Form Integrations allows anchors to define what information needs to be collected from the user. But I've realized that the anchor may want to render non-form content to the user during the interactive flow.

Our particular use case is that when a user submits his/her KYC info (email), the anchor should confirm that the user actually owns that email. We'd do this by sending a confirmation email and rendering a "Please confirm your email before proceeding" page until they confirm. Once they confirm, we'd move on to filling out the rest of the forms.

We should rename form_for_transaction to content_for_transaction