feat(APIM-608): gov notify - file upload/link support

[ttbarnes]

Introduction ✏️

GOV Notify integration needs the ability to consume and send a file buffer, in order for users to be able to download a file stored securly by Notify.

Resolution ✔️

• Update GOV Notify constants.
• Update GOV Notify service to conditionally add a linkToFile property.
• Update PostEmailsRequestDto module to include FILE.
• Create new mock JSON response (for unit tests).

Miscellaneous ➕

• Minor JSON indentation improvement.
• Minor documentation improvment.

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud