Fix bug with collapsible grids inside of group widget

Also move utils to new file

internal/assets/static/js/utils.js

@@ -0,0 +1,25 @@
+export function throttledDebounce(callback, maxDebounceTimes, debounceDelay) {
+    let debounceTimeout;
+    let timesDebounced = 0;
+
+    return function () {
+        if (timesDebounced == maxDebounceTimes) {
+            clearTimeout(debounceTimeout);
+            timesDebounced = 0;
+            callback();
+            return;
+        }
+
+        clearTimeout(debounceTimeout);
+        timesDebounced++;
+
+        debounceTimeout = setTimeout(() => {
+            timesDebounced = 0;
+            callback();
+        }, debounceDelay);
+    };
+};
+
+export function isElementVisible(element) {
+    return !!(element.offsetWidth || element.offsetHeight || element.getClientRects().length);
+}