Static hosting custom header policies

[krishanthisera]

This feature enable us to create and attach response header policies to specified path.
This is an optional configuration.

1. Create a policy

   // Creating a custom response headers policy -- all parameters optional
   const reportUriPolicy = new ResponseHeadersPolicy(this, 'ReportUriPolicy', {
       responseHeadersPolicyName: 'ReportUriPolicy',
       comment: 'To enable CSP Reporting',
       customHeadersBehavior: {
           customHeaders: [
               { 
                   header: 'content-security-policy-report-only', 
                   value: `default-src 'none'; form-action 'none'; frame-ancestors 'none'; report-uri https://some-report-uri-domain.report-uri.com/r/t/csp/wizard`, 
                   override: true 
               },
           ],
       },
   });

2. Attached policy to desired cache behavior or path

   const responseHeaders: ResponseHeaderMappings[] = [{
       header: reportUriPolicy,
       pathPatterns: ['/au*', '/nz*']
       attachToDefault: false
   }];

   If you should attached the policy to the Default Behavior, set attachToDefault: true

3. Include the config as props

   new StaticHosting(this, 'pwa-stack', {...staticProps, ...{behaviors, customOriginConfigs, responseHeaders}});

[crispy101]

LGTM