[versions] update to latest source span and roll engine to  4b8477d11573d233e6791204191c0090f733b05d (#66136)

PR #65873 enabled DDS for non-web Flutter applications. This change
surfaced a bug where DDS would not send ServiceRegistered events to VM
service clients when they subscribed to the Service stream. This would
cause tools and tests that rely on these events (e.g., hot reload in
VSCode) to fail.

Fixes #66038.

This reverts commit df833986.

This reverts commit 12b7355d.

Update to latest dwds, file-nullsafety, and process-nullsafety for #62886

Update prepare_package.dart to use the process_runner package instead having duplicate code. (#62710)

Updates the prepare_package.dart script to use the process_runner package (which is where the ProcessRunner implementation was moved to).

This reverts commit c46aa360.

Revert "Reland "Add support for Dart Development Service (DDS) in Flutter Tools (#61276)" (#61975)" (#61993)

This reverts commit f7a1c87f.

This reverts commit 4867f593.

This reverts commit b7b60a2d.

Revert "Reland "Add support for Dart Development Service (DDS) in Flutter Tools (#61276)" (#61633)" (#61641)

This reverts commit 594c3541.

This reverts commit a1a5a8f6.

Roll packages, update XML deprecations.

Update all versions, specifically file which fixes some bugs that caused tests to fail if run in different orders:

- systemTemp directories created by MemoryFileSystem will allot names based on the file system instance instead of globally.
- MemoryFile.readAsLines()/readAsLinesSync() no longer treat a final newline in the file as the start of a new, empty line.
- RecordingFile.readAsLine()/readAsLinesSync() now always record a final newline.

Fixes #59718

Update all versions, specifically dwds which has a hot restart fix

* Run `flutter update-packages --force-upgrade`.
* Update test to 1.14.5.

* Bump flutter_gallery_assets version to ^0.2.0.

* Run `flutter update-packages --force-upgrade`.

* Add comment.

* Remove duplicate key.

## Description

Removes the `flutter_test` dependency on `quiver`, instead using the more targeted `clock` and `fake_async` packages.

## Related Issues

https://github.com/flutter/flutter/issues/53908

## Tests

No changes to tests

## Checklist

Before you create this PR confirm that it meets all requirements listed below by checking the relevant checkboxes (`[x]`). This will ensure a smooth and quick review process.

- [x] I read the [Contributor Guide] and followed the process outlined there for submitting PRs.
- [x] I signed the [CLA].
- [x] I read and followed the [Flutter Style Guide], including [Features we expect every widget to implement].
- [x] I read the [Tree Hygiene] wiki page, which explains my responsibilities.
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] All existing and new tests are passing.
- [x] The analyzer (`flutter analyze --flutter-repo`) does not report any problems on my PR.
- [x] I am willing to follow-up on review comments in a timely manner.

## Breaking Change

Did any tests fail when you ran them? Please read [Handling breaking changes].

- [ ] No, no existing tests failed, so this is *not* a breaking change.
- [x] Yes, this is a breaking change. *If not, delete the remainder of this section.*
   - [x] I wrote a design doc: https://docs.google.com/document/d/1EkkLbECNBwHgddBQAZqEy7iQLTIxR1rgChKzxcLwhio/edit
   - [x] I got input from the developer relations team, specifically from: @RedBrogdon
   - [x] I wrote a migration guide:  https://github.com/flutter/website/pull/3932

<!-- Links -->
[issue database]: https://github.com/flutter/flutter/issues
[Contributor Guide]: https://github.com/flutter/flutter/wiki/Tree-hygiene#overview
[Test Coverage]: https://github.com/flutter/flutter/wiki/Test-coverage-for-package%3Aflutter
[Flutter Style Guide]: https://github.com/flutter/flutter/wiki/Style-guide-for-Flutter-repo
[Features we expect every widget to implement]: https://github.com/flutter/flutter/wiki/Style-guide-for-Flutter-repo#features-we-expect-every-widget-to-implement
[CLA]: https://cla.developers.google.com/
[Tree Hygiene]: https://github.com/flutter/flutter/wiki/Tree-hygiene
[Handling breaking changes]: https://github.com/flutter/flutter/wiki/Tree-hygiene#handling-breaking-changes

Co-authored-by: Georg Wechslberger <wechslbe@ma.tum.de>