[flutter_migrate] Remove source

[stuartmorgan-g]

The package has been discontinued on pub.dev.

Context for removal:

• It was never fully launched (e.g., the version on pub didn't follow the standard release process).
• It has not been actively developed in more than a year, and has been subject to bitrot (example).
• There are currently no plans to re-staff the project in the foreseeable future in order to get it to a stable state.

Since it's a use-as-needed tool rather than something that applications actively depend on, and it has <100 downloads per month, we are not doing a deprecation period.

[gemini-code-assist]

Code Review

This pull request removes the flutter_migrate package, which is no longer in development. The changes consist of deleting the entire packages/flutter_migrate directory, along with its source code, tests, and documentation. Correspondingly, references to flutter_migrate have been removed from repository configuration files, including .github/labeler.yml, CODEOWNERS, and analysis/testing configuration files in the script/ directory. The changes are straightforward deletions and configuration updates to reflect the package's removal.

[frederikstonge]

@stuartmorgan-g Am I allowed to take the source and maintain it? What are the rules that I have to follow? Keep the copyright on files and the license? Thank you

[stuartmorgan-g]

Am I allowed to take the source and maintain it?

Anyone can use the source in any way that the package's license allows.

What are the rules that I have to follow? Keep the copyright on files and the license?

If you have questions about software licensing, you would need to consult a lawyer; the Flutter team cannot provide you with legal advice.