Render an email template

Render an email template for the given lead/contact using the current user context.

Accepts two forms of usage:

• Single lead/contact:
  • lead_id and contact_id is supplied (both required)
• Preview results from a search query
  • query (required) contains a search query
  • entry (optional, ranges from 0 to 99) specifies the index of the lead/contact that should be rendered.
  • mode (optional), which can have a value of:
    • lead (default), the first contact of the lead with the index given by entry will be rendered (excluding leads that have no email addresses).
    • contact, then entry refers to the index of the contact (excluding contacts that have no emails). Will return an empty dict if there are no more entries.