Added CacheControl support to Headless Server

Headless Server now supports sending CacheControl headers for GET requests using the caas.cache-control.* properties. Values of the validFrom/validTo properties of the requested contents are not taken into account. A configured negative max-age value for a URL pattern indicates that no CacheControl header should be sent even in the presence of a default configuration for a less specific URL pattern, where specificity is defined by the URL order as implemented by org.springframework.util.AntPathMatcher#getPatternComparator .

(CMS-21078)