Template formatting: add headers 4-6

[cris-oddball]

User Story - Business Need

When meeting with the Strike team to discuss template formatting, they indicated that a 'nice to have' for email templates would be headers 4-6, which we currently convert to paragraph text. This ticket aims to add formatting for H4 through H6.

• Ticket is understood, and QA has been contacted (if the ticket has a QA label).

User Story(ies)

As a VANotify client
I want headers 4-6 to have formatting
So that I can send the type of emails I want to send.

Additional Info and Resources

• Template ID 86820037-1374-4072-9f9f-e74f235170a1 in the Dev VANotify service includes these headers for your use in testing.
• Elissa should be consulted as to what the style should be on the new headers.

Engineering Checklist

• Discuss what the formatting should look like with Elissa on the Strike team
• Headers 4 through 6 have that formatting style applied for email templates
• Unit tests

Acceptance Criteria

• This work is added to the sprint review slide deck (key win bullet point and demo slide)
• When I create or update a template in the Portal, I can add in the markdown for headers 4-6
• When I add in the markdown for headers 4-6, the Portal preview displays the formatting as intended
• When I send an email using that template, the received email displays the formatting as intended
• Before the PR is merged, the work is reviewed with Strike for their approval
• Strike is notified in #va-notifications-va-gov-program when the work is completed

QA Considerations

• Validate different header options in the Portal and by sending email.