This major release is mostly about keeping import map for node module and writing importmap file separated.

- replace generateImportMapForProjectPackage by getImportMapFromNodeModules
- getImportMapFromNodeModules only return importmap, it does not write to filesystem anymore.
- add getImportMapFromFile
- add generateImportMapForProject
- generate importmap for package self ref by default
see https://github.com/nodejs/node/pull/31002
- rename some parameter like favoredExports becoming packagesExportsPreference
- ensure a package self reference is stronger than self dev dependency