feat(task-management): improve dropdown behavior and enhance task row components

- Updated AssigneeSelector and LabelsSelector to close dropdowns only when scrolling outside the dropdown area, enhancing user experience.
- Introduced TaskLabelsCell component in TaskRow for better label rendering and organization.
- Refactored date handling in TaskRow to consolidate formatted date logic and improve clarity.
- Memoized date picker handlers for better performance and cleaner code.

worklenz-frontend/src/components/AssigneeSelector.tsx

@@ -88,10 +88,12 @@ const AssigneeSelector: React.FC<AssigneeSelectorProps> = ({
       }
     };
 
-    const handleScroll = () => {
+    const handleScroll = (event: Event) => {
       if (isOpen) {
-        // Close dropdown when scrolling to prevent it from moving with the content
-        setIsOpen(false);
+        // Only close dropdown if scrolling happens outside the dropdown
+        if (dropdownRef.current && !dropdownRef.current.contains(event.target as Node)) {
+          setIsOpen(false);
+        }
       }
     };