Improve caching, HTTP headers and URL handling (#3594)

* Fix relative URLs
* Improve login base URL and redirects
* Prevent duplicate customlocales requests
* Improve UI base URL handling
* Improve UI embedding
* Improve CSP header
* Add Cache-Control headers to all responses
* Improve CORS responses
* Improve authentication handler
* Add back media timestamp suffixes
* Fix default image handling
* Add default param to other image URLs

ui/v2.5/src/components/MainNavbar.tsx

@@ -32,6 +32,7 @@ import {
   faUser,
   faVideo,
 } from "@fortawesome/free-solid-svg-icons";
+import { baseURL } from "src/core/createClient";
 
 interface IMenuItem {
   name: string;
@@ -256,7 +257,7 @@ export const MainNavbar: React.FC = () => {
       return (
         <Button
           className="minimal logout-button d-flex align-items-center"
-          href="/logout"
+          href={`${baseURL}logout`}
           title={intl.formatMessage({ id: "actions.logout" })}
         >
           <Icon icon={faSignOutAlt} />