feat(storage): add Apple iCloud Drive storage provider

Add iCloud Drive as a new storage destination using the pyicloud library.
Includes upload task, configuration, user integration handler, provider
status, onboarding support, and comprehensive tests.

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

tests/test_send_to_all.py

@@ -300,6 +300,7 @@ class TestSendToAllDestinations:
         mock_sftp.return_value = False
         mock_email.return_value = False
         mock_onedrive.return_value = False
+        mock_icloud.return_value = False
         mock_dropbox_upload.delay.return_value = MagicMock(id="dropbox-task")
         mock_s3_upload.delay.return_value = MagicMock(id="s3-task")