Factor out popup menu component.

Factor out the popup menu inside user tooltips into a reusable
component.

app/javascript/src/javascripts/user_tooltips.js

@@ -25,19 +25,6 @@ UserTooltip.initialize = function () {
     onShow: UserTooltip.on_show,
     onHide: UserTooltip.on_hide,
   });
-
-  delegate("#user-tooltips", {
-    allowHTML: true,
-    interactive: true,
-    theme: "common-tooltip",
-    target: ".user-tooltip-menu-button",
-    placement: "bottom",
-    touch: false,
-    trigger: "click",
-    content: (element) => {
-      return $(element).parents(".user-tooltip").find(".user-tooltip-menu").get(0);
-    }
-  });
 };
 
 UserTooltip.on_show = async function (instance) {

app/javascript/src/styles/specific/user_tooltips.scss

@@ -57,29 +57,11 @@
       font-size: 0.75em;
     }
 
-    a.user-tooltip-menu-button {
-      color: var(--muted-text-color);
+    div.popup-menu {
       grid-area: menu;
       align-self: center;
-      text-align: center;
       width: 28px;
       height: 28px;
-      line-height: 28px;
-      border-radius: 50%;
-
-      &:hover {
-        background-color: var(--subnav-menu-background-color);
-      }
-    }
-
-    > ul.user-tooltip-menu {
-      display: none;
-    }
-
-    ul.user-tooltip-menu {
-      .icon {
-        width: 1.5em;
-      }
     }
   }