Description of change

Added a maxLengthEnforcement parameter using the
new enum type MaxLengthEnforcement,
as a replacement for the now-deprecated boolean
maxLengthEnforced parameter on
TextField, TextFormField, CupertinoTextField, and
LengthLimitingTextInputFormatter classes.

Migration guide

Using the default behavior for the current platform is recommended,
since this will be the behavior most familiar to the user.

Default values of maxLengthEnforcement

Android, Windows: MaxLengthEnforcement.enforced.
The native behavior of these platforms is enforced.
The inputting value will be truncated whether
the user is entering with composition or not.