feat: Switch to mjml to handle email templates

[arsforza]

closes #1515

Describe your changes

• Install mjml
• Migrate to object structure
• Test for multiple disasters

Checklist before requesting a review

• I have performed a self-review of my code
• I have added tests wherever relevant
• I have made sure that all automated checks pass before requesting a review

[gulfaraz]

Reviewed over a call with @arsforza

Change Requests

• Breakpoint - email should take full width in mobile
• Font - use the same font as in the emails before this change
• Button border-radius - button-radius does not work in outlook
• Add space between button and text in mobile where the button and text is stacked instead of next to each other
• Add space after Advisory in the event text
• In event text it reads "from nows from now"
• Button labels are different (maybe this gets fixed after merge to master)
  • Open IBF
  • Join WhatsApp
  • About Trigger
• Mailchimp footer does not match the old emails
  • Add some padding-top
• Do a manual comparison of the copy from the emails generated in the master branch

Relevant Links

• ibf-emails
• mj-button is rendered without border radius in Outlook 2016 with valid links mjmlio/mjml#2394
• https://mjml.io/compatibility/mj-button#attribute-border-radius
• https://mailchimp.com/help/customize-your-footer-content

[gulfaraz]

@arsforza I missed one change in our review call. Let's use date-fns instead of moment/luxon. Refer to this comment for context.

[gulfaraz]

#1594