tippy: Add delay for recipient bar icons.

This commit adds a long hover delay [750,20] to recipient bar icons.
Doing this prevents the situation when the tippy tooltips are left
floating when the icons suddenly disappear as you enter the topics
according to the organization settings and the references are removed.
Adding an additional delay ensures that the icons disappear and then
the tooltips appear.

web/src/tippyjs.js

@@ -416,6 +416,7 @@ export function initialize() {
     });
 
     message_list_tooltip([".recipient_bar_icon"], {
+        delay: LONG_HOVER_DELAY,
         onHidden(instance) {
             instance.destroy();
         },