Per host security headers

## Feature request

### Feature description

I'd like to have Content-Security-Policy header different for different domains.

### How the feature is useful

If I have one domain running WordPress, which requires `unsafe-eval`, I want it only on this domain, not on others.

The issue names no files, tests, or entry points. Start by locating the NGINX configuration-generation path and establish how per-domain Content-Security-Policy settings should be specified; done means different domains can receive different policies, including domain-specific unsafe-eval, without changing other domains.

Written by the indexing model from the issue text.