[WIP] Add more guidance around sending email via templates

[patcon]

To Do

• mvp component design
• demo component to @s-kennedy (feedback)
  • use better "template preview" link
  • open links in _blank tab
  • mention Mailjet to hint at external system
  • warn about login being required (tooltip?)
  • other discussion items
    • listing for failed/bounced/success emails
    • confirms no good way to link to this within mailjet (no way to filter)
• seek feedback from StART team
• if get go-ahead
  • add server logic for passing template variables
  • maybe: display template labels in component
• fix storybook workflow
• auto-link hosted storybook from PRs
• add new storybook build workflow for send_email app

[patcon]

Had quick review with @s-kennedy. loose notes:

• use better "template preview" link
• open links in _blank tab
• mention Mailjet to hint at external system
• warn about login being required (tooltip?)
• other discussion items
  • maybe: listing for failed/bounced/success emails
    • confirmed no good way to link to this within mailjet (no way to filter from link, so a bit confusing to link there)
    • not good enough: single email logs https://app.mailjet.com/reports/emails/GAcaU3q0oT
    • not good enough: stats page https://app.mailjet.com/stats
    • examples: "blocked" = template var error https://app.mailjet.com/reports/emails/1naolIo4nfJ
      • also "soft-bounce", "hard-bounce", "spam", but no examples yet
  • label which templates are automated, etc, perhaps using mailjet template labels