Package name field

It occurs me that the `Package` entity doesn't have a name field. This may present a problem if the user only has access to the custom-elements.json, but not the package.json

for example, when pre-loading manifests into a language server, a la https://github.com/Matsuuu/custom-elements-language-server/issues/20

Start by locating the Package entity in the custom-elements-manifest schema and review how custom-elements.json represents package metadata without package.json. Check the language-server use case linked in the issue to understand the needed value. Done means a Package name can be read directly from custom-elements.json for consumers that lack package.json.

Written by the indexing model from the issue text.