transfer package:file, package:file_testing

[devoncarew]

• move and fix workflow files
• enable 'Allow merge commits' in GitHub settings; merge the PR with 'Create a merge commit'; disable 'Allow merge commits'
• push tags to GitHub using git tag --list 'file*' | xargs git push origin
• follow up with a PR adding links to the top-level readme table
• transfer issues by running dart run pkgs/repo_manage/bin/report.dart transfer-issues --source-repo dart-lang/file --target-repo dart-lang/tools --add-label package:file --apply-changes
• update the auto-publishing settings on pub.dev/packages/file
• add a commit to https://github.com/dart-lang/file/ with it's readme pointing to the monorepo
• archive https://github.com/dart-lang/file/

---

• I’ve reviewed the contributor guide and applied the relevant portions to this PR.

Contribution guidelines:

• See our contributor guide for general expectations for PRs.
• Larger or significant changes should be discussed in an issue before creating a PR.
• Contributions to our repos should follow the Dart style guide and use dart format.
• Most changes should add an entry to the changelog and may need to rev the pubspec package version.
• Changes to packages require corresponding tests.

Note that many Dart repos have a weekly cadence for reviewing PRs - please allow for some latency before initial review feedback.

[google-cla]

Thanks for your pull request! It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

View this failed invocation of the CLA check for more information.

For the most up to date status, view the checks section at the bottom of the pull request.

[github-actions]

PR Health

Changelog Entry ✔️

Package	Changed Files

Changes to files need to be accounted for in their respective changelogs.

API leaks ✔️

The following packages contain symbols visible in the public API, but not exported by the library. Export these symbols or remove them from your publicly visible API.

Package	Leaked API symbols

License Headers ✔️

// Copyright (c) 2024, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

Files
no missing headers

All source files should start with a license header.

Package publish validation ✔️

Package	Version	Status
package:cli_config	0.2.1-wip	WIP (no publish necessary)
package:coverage	1.9.2	already published at pub.dev
package:extension_discovery	2.1.0	already published at pub.dev
package:file	7.0.1-wip	WIP (no publish necessary)
package:file_testing	3.0.1-wip	WIP (no publish necessary)
package:graphs	2.3.3-wip	WIP (no publish necessary)
package:mime	2.0.0	already published at pub.dev
package:oauth2	2.0.4-wip	WIP (no publish necessary)
package:source_map_stack_trace	2.1.3-wip	WIP (no publish necessary)
package:unified_analytics	6.1.4	already published at pub.dev

Documentation at https://github.com/dart-lang/ecosystem/wiki/Publishing-automation.