Add ExpiryIndicator binding functionality and UI enhancements

- Introduced a new button in the portal settings to bind the ExpiryIndicator to existing date fields.
- Added a modal dialog for binding configuration, including fields for web URL, list title, and internal field name.
- Enhanced the ExpiryIndicator panel to include options for loading and saving site collection defaults.
- Updated the JavaScript functions to handle binding logic and validation for the ExpiryIndicator.
- Improved the user interface for better usability and clarity in the portal settings page.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "portal-settings",
-  "version": "2.0.0",
+  "version": "2.1.0",
   "private": true,
   "main": "lib/index.js",
   "engines": {