Add missing ESM export of NodePackageImporter (#2177)

Co-authored-by: Natalie Weizenbaum <[email protected]>

Author: jgerigmeyer

CHANGELOG.md

@@ -4,6 +4,10 @@
 
 * Ship the musl Linux release with the proper Dart executable.
 
+### JavaScript API
+
+* Export the `NodePackageImporter` class in ESM mode.
+
 ### Embedded Sass
 
 * In the JS Embedded Host, properly install the musl Linux embedded compiler

tool/grind.dart

@@ -84,6 +84,7 @@ void main(List<String> args) {
     'FALSE',
     'NULL',
     'types',
+    'NodePackageImporter',
   };
 
   pkg.githubReleaseNotes.fn = () =>