4554 [webview_flutter] Updates webview_flutter_platform_interface to version 1.5.2 (cla: yes, p: webview_flutter, platform-ios, needs tests)

4566 [webview_flutter] Revert deprecation of clearCookies (cla: yes, p: webview_flutter, needs tests)

4596 [shared_preferences] Remove platform registration (waiting for tree to go green, p: shared_preferences, needs tests)

4598 Add missing return for nullably typed function (waiting for tree to go green, needs tests)

4600 [webview_flutter] Change import of FLTCookieManager.h to relative import (waiting for tree to go green, p: webview_flutter, platform-ios, needs tests)