Add option to allow extra domains in the auth cookie other than the one in base url (#39)

* Add CONFIG_ALLOWED_COOKIE_DOMAINS option

* Apply suggestions from @BrunoBernardino

---------

Co-authored-by: Bruno Bernardino <me@brunobernardino.com>

lib/config.ts

@@ -20,6 +20,16 @@ export function isAppEnabled(app: 'news' | 'notes' | 'photos') {
   return enabledApps.includes(app);
 }
 
+export function isCookieDomainAllowed(domain: string) {
+  const allowedDomains = (Deno.env.get('CONFIG_ALLOWED_COOKIE_DOMAINS') || '').split(',') as typeof domain[];
+  
+  if (allowedDomains.length === 0) {
+    return true;
+  }
+
+  return allowedDomains.includes(domain);
+}
+
 export function isEmailEnabled() {
   const areEmailsAllowed = Deno.env.get('CONFIG_ENABLE_EMAILS') === 'true';