Add support for 'require-trusted-types-for' policy

[MrPropre]

https://w3c.github.io/webappsec-trusted-types/dist/spec/#require-trusted-types-for-csp-directive

[paragonie-security]

This is still marked as experimental: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy/require-trusted-types-for