Merge package:test_descriptor

[mosuem]

• Move and fix workflow files, labeler.yaml, and badges in the README.md
• Rev the version of the package, so that pub.dev points to the correct site
• Add a line to the changelog:

* Move to `dart-lang/test` monorepo.

• Add the package to the top-level readme of the monorepo:

| [test_descriptor](pkgs/test_descriptor/) | An API for defining and verifying files and directory structures. | [![package issues](https://img.shields.io/badge/package:test_descriptor-4774bc)](https://github.com/dart-lang/tools/issues?q=is%3Aissue+is%3Aopen+label%3Apackage%3Atest_descriptor) | [![pub package](https://img.shields.io/pub/v/test_descriptor.svg)](https://pub.dev/packages/test_descriptor) |

• Important! Merge the PR with 'Create a merge commit' (enabling then disabling the Allow merge commits admin setting)
• Update the auto-publishing settings on https://pub.dev/packages/test_descriptor/admin
• Add the following text to https://github.com/dart-lang/test_descriptor/:'

> [!IMPORTANT]  
> This repo has moved to https://github.com/dart-lang/test/tree/master/pkgs/test_descriptor

• Publish using the autopublish workflow
• Push tags to GitHub using

git tag --list 'test_descriptor*' | xargs git push origin

• Close open PRs in dart-lang/test_descriptor with the following message:

Closing as the [dart-lang/test_descriptor](https://github.com/dart-lang/test_descriptor) repository is merged into the [dart-lang/test](https://github.com/dart-lang/test) monorepo. Please re-open this PR there!

• Transfer issues by running

dart run pkgs/repo_manage/bin/report.dart transfer-issues --source-repo dart-lang/test_descriptor --target-repo dart-lang/test --add-label package:test_descriptor --apply-changes

• Archive https://github.com/dart-lang/test_descriptor/

---

• 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]

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

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[github-actions]

PR Health

Changelog Entry ✔️

Package	Changed Files

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

[github-actions]

Package publishing

Package	Version	Status	Publish tag (post-merge)
package:test_descriptor	2.0.2	ready to publish	test_descriptor-v2.0.2
package:checks	0.3.1-wip	WIP (no publish necessary)
package:fake_async	1.3.2	already published at pub.dev
package:matcher	0.12.18-wip	WIP (no publish necessary)
package:test	1.25.14	already published at pub.dev
package:test_api	0.7.4	already published at pub.dev
package:test_core	0.6.8	already published at pub.dev
package:test_process	2.1.1	already published at pub.dev

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