Improve UI of IconButton when disabled

app/soapbox/components/ui/icon-button/icon-button.tsx

@@ -25,6 +25,7 @@ const IconButton = React.forwardRef((props: IIconButton, ref: React.ForwardedRef
       type='button'
       className={classNames('flex items-center space-x-2 p-1 rounded-full focus:outline-none focus:ring-2 focus:ring-offset-2 dark:ring-offset-0 focus:ring-primary-500', {
         'bg-white dark:bg-transparent': !transparent,
+        'opacity-50': filteredProps.disabled,
       }, className)}
       {...filteredProps}
       data-testid='icon-button'