Installing a plugin with --link does not links the javascript file.

# Bug Report

## Problem
When developing a plugin, if the plugin is installed using the `--link` flag each change in the source Java File is applied to the plugin on next build (the file is a symlink). The same does not happens with the JavasSript file.

### What is expected to happen?
Te JavaScript file should also be somehow linked

### What does actually happen?
An old javascript file lives in `platforms\android\platform_www\plugins\cordova-plugin-some-name\www\SomePlugin.js`

## Information
As work around I use a script that appends de cordova wrapper to my javascript file and copy it.

### Command or Code

cordova install some-plugin --link

### Environment, Platform, Device
Tested in Windows 10 with 9.0.0 (cordova-lib@9.0.1)

### Version information

## Checklist

- [x] I searched for existing GitHub issues
- [x] I updated all Cordova tooling to most recent version
- [x] I included all the necessary information above