tippy: Use namespace import for tippy.js.

Names like “delegate”, “Instance”, “Placement”, “Props”, and
“ReferenceElement” are much too generic to make sense as named
imports.

The downside is that we now need to write tippy.default(…) instead of
tippy(…) (because ES module namespace objects cannot be callable), but
that cost is worthwhile.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

web/src/buddy_list.ts

@@ -1,6 +1,6 @@
 import $ from "jquery";
 import assert from "minimalistic-assert";
-import tippy from "tippy.js";
+import * as tippy from "tippy.js";
 
 import render_section_header from "../templates/buddy_list/section_header.hbs";
 import render_view_all_subscribers from "../templates/buddy_list/view_all_subscribers.hbs";
@@ -166,7 +166,7 @@ export class BuddyList extends BuddyListConf {
                     // This will default to "bottom" placement for this tooltip.
                     placement = "auto";
                 }
-                tippy($elem[0], {
+                tippy.default($elem[0], {
                     // Because the buddy list subheadings are potential click targets
                     // for purposes having nothing to do with the subscriber count
                     // (collapsing/expanding), we delay showing the tooltip until the