WSTEAM1-1068: Add csp next

[shayneahchoon]

Resolves JIRA WSTEAM1-1068

Overall changes

Add the following csp headers onto the Next.js app:

 policiesFromExpress= [
  'default-src',
  'child-src',
  'connect-src',
  'font-src',
  'frame-src',
  'img-src',
  'script-src',
  'style-src',
  'media-src',
  'worker-src',
  'report-to',
  'upgrade-insecure-requests',
];

Code changes

• Next.js middleware function altered to append csp onto both the request and response headers.
• Helmet csp function in the express app refactored to prevent dependency resolution errors from Next.js app.

Testing

1. List the steps used to test this PR.

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[amoore108]

Looks good! I'd test this on the Preview environment first against some Live page assets that have embeds/video players on them just to be sure.

[emilysaffron]

🎉