chore: optionally prefix authentication related cookies (#22148)

When the deployment option is enabled auth cookies are prefixed with
`__HOST-`
([info](https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Set-Cookie)).

This is all done in a middleware that intercepts all requests and strips
the prefix on incoming request cookies.

site/src/api/typesGenerated.ts

@@ -2335,6 +2335,7 @@ export interface GroupSyncSettings {
 export interface HTTPCookieConfig {
 	readonly secure_auth_cookie?: boolean;
 	readonly same_site?: string;
+	readonly host_prefix?: boolean;
 }
 
 // From health/model.go