feat: add CSP header to all the pages

[DiogoSoaress]

What it solves

Adds an explicit Content Security Policy to the website pages

How this PR fixes it

Sets the Content Security Policy through a <meta> tag

I tried to keep the allowed src lists as restrictive as possible without braking anything or lose of functionality

[github-actions]

Branch preview

✅ Deployed successfully in branch deployment:

https://csp--homepage.review.5afe.dev

[schmanu]

Looks good to me.

Some rules are quite strict. If you experience that sometimes those id's or filenames change you could also allow the entire origin or the higher path as src.
e.g.
https://cdn.contentful.com/spaces/1i5gc724wjeu/
=>
https://cdn.contentful.com/spaces/

But if the ID is always fixed, being more strict is better :)

[DiogoSoaress]

But if the ID is always fixed

Yes, in this case the Contentful space ID remains the same