Restructure frontend code to allow for extensions (#4721)

# Description of Changes
Move frontend code into `core` folder and add infrastructure for
`proprietary` folder to include premium, non-OSS features

frontend/src/core/utils/genericUtils.ts

@@ -0,0 +1,42 @@
+/**
+ * DOM utility functions for common operations
+ */
+
+/**
+ * Clamps a value between a minimum and maximum
+ * @param value - The value to clamp
+ * @param min - The minimum allowed value
+ * @param max - The maximum allowed value
+ * @returns The clamped value
+ */
+export function clamp(value: number, min: number, max: number): number {
+  return Math.min(Math.max(value, min), max);
+}
+
+/**
+ * Safely adds an event listener with proper cleanup
+ * @param target - The target element or window/document
+ * @param event - The event type
+ * @param handler - The event handler function
+ * @param options - Event listener options
+ * @returns A cleanup function to remove the listener
+ */
+export function addEventListenerWithCleanup(
+  target: EventTarget,
+  event: string,
+  handler: EventListener,
+  options?: boolean | AddEventListenerOptions
+): () => void {
+  target.addEventListener(event, handler, options);
+  return () => target.removeEventListener(event, handler, options);
+}
+
+/**
+ * Checks if a click event occurred outside of a specified element
+ * @param event - The click event
+ * @param element - The element to check against
+ * @returns True if the click was outside the element
+ */
+export function isClickOutside(event: MouseEvent, element: HTMLElement | null): boolean {
+  return element ? !element.contains(event.target as Node) : true;
+}