More specific scaffoled gitignore regarding *.js

atm the default .gitignore has the line `*.js`, this leads to problems, when you have cdk in the root folder of your project and any javascript project in a subfolder.

Personally I had a vuejs project in a subfolder, which failed to build in CI, because files were missing because of the CDK gitignore

### Proposed Solution

switch scaffolded .gitignore to
```
bin/*.js
lib/*.js
```

* [ ] :wave: I may be able to implement this feature request
* [ ] :warning: This feature might incur a breaking change

---

This is a :rocket: Feature Request

Locate the scaffolded .gitignore template responsible for the default `*.js` entry and inspect how CDK projects are generated. Verify the generated file uses `bin/*.js` and `lib/*.js`, while JavaScript files in nested projects remain available to CI.

Written by the indexing model from the issue text.