fix: follow the symlinks in JavaScript apps

[DimitarTachev]

We are already following the symlinks in TypeScript, Angular and Vue apps. It allows the plugin developers to link and develop their plugins directly in a JavaScript demo application

PR Checklist

• The PR title follows our guidelines: https://github.com/NativeScript/NativeScript/blob/master/CONTRIBUTING.md#commit-messages.
• There is an issue for the bug/feature this PR is for. To avoid wasting your time, it's best to open a suggestion issue first and wait for approval before working on it.
• You have signed the [CLA].
• All existing tests are passing: https://github.com/NativeScript/nativescript-dev-webpack/blob/master/CONTRIBUTING.md#testing-locally-by-running-e2e-tests
• Tests for the changes are included.

Related to: #656