Support linking packages

It's a nice user experience for consumers when a set of related packages all share the same version number. For example:
* `framework@2.3.0`
* `framework-plugin-foo@2.3.0`
* `framework-plugin-bar@2.3.0`

The original changesets tool describes the feature here:
https://github.com/changesets/changesets/blob/main/docs/linked-packages.md.