js/{closure,commonjs}: create a new js_module option

What language does this apply to?

If it's a proto syntax change, is it for proto2 or proto3? proto3
If it's about generated code change, what programming language? javascript/commonjs but it can be applied to es6 or closure as well.

Describe the problem you are trying to solve.

We are generating code of multiple packages that we want to publish independently but with references between them. Currently the generator creates a tightly coupled relative paths between folders.

Describe the solution you'd like

An option like Go's go_package or C#'s csharp_namespace where I can put the import path, in this case the JS module.

I think a js_module called option would do the trick.

Describe alternatives you've considered

Overriding the generated code.

Beginne damit, die Behandlung relativer Importe durch den JavaScript-Generator für CommonJS-, ES6- und Closure-Ausgabe zu lesen, und sieh dir anschließend die Diskussion zu diesem Issue bezüglich der vorgeschlagenen js_module-Semantik an. Die Aufgabe ist erledigt, wenn eine Option unabhängige Modulimportpfade festlegen kann und dabei Verweise zwischen generierten Paketen über die unterstützten JavaScript-Ziele hinweg erhalten bleiben.