Simplify RWPM parsing for packaged publications

[mickael-menu]

• Don't remove the self link anymore, when parsing a packaged publication. They are not supposed to contain a self link with an absolute URL.
• Fix file extensions in the LCP service.
• Restore visibility of MediaSessionNavigator properties (hiding them was a mistake when migrating to the explicit API mode).

[qnga]

You can now revert the change in ParserAssetFactory and use again asset.resource instead of the parsed manifest.