This enables primary-constructors and private-named-parameters by default in CFE expectation tests.
Test are update accordingly; some are annotated with `@dart=3.10` to opt out of the features, some cloned to support both opt-in and opt-out, and some are modified to use opt-in before only.
Part of #61700
Change-Id: Iae9e5d188d9b49d4264d17dc989dbaeee7321845
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/479620
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Johnni Winther
32b6f24e4d