Fix js generator for commonjs_strict

[eKazim]

This resolves js issues when generator used with import_style=commonjs_strict.
The problem was in js-exports that are have nested namespaces. For comparison, when using import_style=commonjs, there is no addiontal nesting in exported objects. So, now js-export is unified, and the use of imported modules is fixed.
This fixes protocolbuffers/protobuf-javascript#40.
Initially, the incorrect generation was made by a commit 13f94b4. In current pr this commit is partially reverted with the correction of incorrect tests.

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[eKazim]

@googlebot I signed it!

[Ty3uK]

@lukesandberg, review PR, please

[eKazim]

Can someone review this PR please?
And I can't add the required labels (release notes: yes, javascript) cause I do not have permission.

[jenseng]

Would love to see this reviewed/merged!

In the meantime I found a workaround, but it only works is your protos don't reference each other, so YMMV. For example, if you have a standalone messages.proto like so:

syntax = "proto3";
package foo.bar.v1;

message A {
  string value = 1;
}

You can make a shim module messagesHack.ts like so:

// export both the types and the implementation 
export * from './messages';
// override the exported implementation
module.exports = require('./messages').foo.bar.v1;

And then import/use stuff from messagesHack like you would normally import messages

[avm99963]

Sorry, I added a comment here but I confused this PR with PR 8864. I apologize for the confusion!

[eKazim]

Any updates of this?

[acozzette]

We are closing all open JavaScript pull requests because the JavaScript implementation is moving to a new repository: https://github.com/protocolbuffers/protobuf-javascript Sorry for the inconvenience but please feel free to reopen the pull request in the new repo.

[eKazim]

@acozzette, Why was it necessary to separate Javascript into a separate repository? Am I right to guess that there is no maintainers for support this?