Add preview of dynamic template emails

Summary

Allow Bank Organizations to preview their email templates

Background references, notes

We send a variety of emails, including some that can be customized and ones that can be enable/disabled. For the customizable emails (Reminder email and Distribution email) we should let the user preview what it'll look like.

• In the My Organization -> Edit screen
• Add a button/link for each of the types of email
• Expand inline with a preview. Fill in mock data all rendered template values
• Fill in a fixed value for each of the template fields (not specific to the Bank Organization)
• Show the whole email, which is both the overall email and the customizable sections

Criteria for completion / testing needs

• For the reminder and distribution emails, add a "preview" button that fills in template values with examples (not from their Org)
• Add a request or system spec to verify the behavior