Implement hoverpic using stimulus.

assets/controllers/elements/hoverpic_controller.js

@@ -0,0 +1,20 @@
+import {Controller} from "@hotwired/stimulus";
+import {Popover} from "bootstrap";
+
+export default class extends Controller {
+    connect() {
+        const thumbnail_url = this.element.dataset.thumbnail;
+
+        this._popover = Popover.getOrCreateInstance(this.element, {
+            html: true,
+            trigger: 'hover',
+            placement: 'right',
+            container: 'body',
+            content: function () {
+                return '<img class="img-fluid" src="' + thumbnail_url + '" />';
+            }
+        });
+
+        this._popover.hide();
+    }
+}