* Use `curly_braces_in_flow_control_structures` for `material`

* include test/material

* add back removed comments

* migrates lib/foundation and lib/widgets

* migrates lib/painting and lib/material

* migrates lib/cupertino, lib/gestures, lib/services, lib/semantics and lib/rendering

* fixes failing tests

* migrates test/

* improves hashing of lists

Added the ability to bring up the date picker dialogs in calendar or text input only modes that don't allow the user to switch. (#76343)

Date Picker restructuring. Moved files out of 'pickers' and merged several of the non-public implementation files into date_picker.dart.