We need to undo the changes to make the repo tooling non-published (publish-to: none, no changelog, etc), and undeprecate https://pub.dev/packages/flutter_plugin_tools.

Ideally we should also get autopublishing set up, but that doesn't have to be blocking since this is not something I expect we'll actually need to update for core-packages frequently (i.e., most changes to the tool won't need to trigger a publishing cycle, as we'll mostly only need them locally).

As part of making this useful, we need to address #185364