tippy: Fix sidebar toggle button tooltip not hidden on blur.

Tabbing through the navbar elements, `Hide user list` tooltip
stays visible even if focus is moved away from it.

We move tooltip to the element receiving focus and blur event
to fix it. See previous commit for more details.

web/src/tippyjs.ts

@@ -622,7 +622,7 @@ export function initialize(): void {
     });
 
     tippy.delegate("body", {
-        target: "#userlist-toggle",
+        target: "#userlist-toggle-button",
         delay: LONG_HOVER_DELAY,
         placement: "bottom",
         appendTo: () => document.body,