Code Review

This pull request introduces validation during DevTools extension discovery and validation to ensure that an extension's declared name in config.yaml matches its containing package name. If there is a mismatch, the extension is ignored (with a warning) or validation fails. This is implemented across devtools_shared and devtools_extensions, with corresponding tests added.

Feedback on the changes highlights two potential runtime issues:

1. In extension_manager.dart, if the name field in config.yaml is missing or not a string, the extension will be silently ignored with a mismatch warning instead of throwing a more descriptive parsing error. It is suggested to only perform the mismatch check if extensionName is a String.
2. In _validate.dart, casting pubspecYaml['name'] and configYaml['name'] directly using as String? can cause a runtime TypeError if the fields are parsed as non-string types. Safe type checking should be used instead.

The actually breaks an intentional feature of DevTools extensions that allows you to develop your extension in a different package than the one where you ship it. See https://github.com/rrousselGit/provider/tree/master/packages for an example. This is necessary because many package authors want to decouple their Flutter Web project (DevTools extension) from their package that users import as a direct dependency. Developing the devtools extension in another package allows the Flutter web code and deps to be kept separate from the package users depend on.