Add application settings page

[mkimberlin]

As an administrator, I want a dedicated page to manage all application settings so that I can easily manage application functionality.

Acceptance Criteria:

• A new menu item titled "Settings" is added under the "ADMIN" menu
  • The new menu item is visible only to users with the "CAN_ADMINISTER_SETTINGS" permission.
• The "Settings" page displays a list of all settings retrieved from the settings options service.
• Settings are grouped by category.
• Each setting displays a text entry field for editing the value with the current value populated.
• Editing a setting triggers a call to the appropriate REST service to save the new value.
• Upon successful saving, a confirmation message is displayed.
• The page reflects the updated settings value after saving.
• Error messages are displayed for any failures.

[mkimberlin]

This one has some unfinished Acceptance Criteria and is free to be picked up and finished off.