* Reland "Add --serve-observatory flag to run, attach, and test (#118402)"

This reverts commit 86ab01d2.

* Fix flaky failures

* Fix VM service disappearing failure

This reverts commit 6cd4fa45.

This flag will allow for Observatory to be served by the VM service once it is disabled by default in the Dart SDK.

* dart fix --apply

* manual fixes

* fix after merge conflicts

* review

* remove all body_might_complete_normally_catch_error ignores

* add a test

Revert "Read dart_plugin_registrant path from FlutterProject to support non-standard path." (#107850)

This PR adds extra timings for a hot reload.
As an example, before a user might see

> Performing hot reload...                                                
> Reloaded 1 of 788 libraries in 554ms.

With this PR it would instead be something like

> Performing hot reload...                                                
> Reloaded 1 of 788 libraries in 554ms (compile: 33 ms, reload: 153 ms, reassemble: 310 ms).

This reverts commit 1d9edde0.

This reverts commit 5fd259be.

Building an application for a desktop platform that transitively included any Dart-based plugins (such as path_provider) broke `flutter test`, because its compilation was overriding the provided main (in this case, the test main) with `generated_main.dart` if it was present. This PR:
- Changes the `flutter test` compilation path to update `generated_main.dart`, so that the tests will work, and will include any registered Dart plugins.
- Makes using `generated_main.dart` during recompile opt-in, to try to reduce the chance of a similar bug happening with other codepaths in the future.

Fixes https://github.com/flutter/flutter/issues/88794

* Add new hook for setupHotReload and after updating devFS is complete

* Handle the case where updateDevFS failed

This adds avoid_dynamic_calls to the list of lints, and fixes all instances where it was violated.

Importantly, this lint is NOT turned on for flutter/packages/test, because those changes are happening in another PR: #84478