This reverts commit 027d4eca.

Revert "[flutter_tools] remove mocks, globals from golden comparator and test runner tests (#81423)" (#81487)

This reverts commit 8fe4cc79.

* opt out the flutter tool

* oops EOF

* fix import

* Update tool_backend.dart

* Update daemon_client.dart

* fix more

[flutter_tools] use initially parsed package config for language version, sound mode determination (#70323)

* [flutter_tools] null safety mode is used for dill naming

* add bad test case

This reverts commit 66b01c1f.

* Add DDS ipv6 support

* Use --dds-port for DDS instead of hijacking --host-vmservice-port

This reverts commit c8f234d3.

This reverts commit 2436de13.

This reverts commit eef0050d.

* Reland "Re-enable the Dart Development Service (DDS) (#64671)"

This reverts commit 2ae25cc2.

* Fix MDNS building Observatory URI with port 0 instead of forwarding the device port

* Added MDNS test

This reverts commit d7d12412.

This change re-enables DDS and outputs the DDS URI in place of the VM
service URI on the console. If --disable-dds is not provided,
--host-vmservice-port will be used to determine the port for DDS rather
than the host port for the VM service, which will instead be randomly
chosen.

Also combines experiments into extraGenSnapshot/ExtraFrontEndOptions. Allows providing --no-sound-null-safety to allow out of order migration and running.

Support --enable-experiment in flutter test (for flutter_tester). Required minor change for null safety.

Update to latest dwds APIs, moving back to dwds driven hot restart and enabling future work on expression evaluation.