Initial Infrastructure setup doesn't work on a Windows machine

Running the infrastructure-setup.sh doesn't work on a Windows machine. The issue is with the cdk.json file and how the app is specified. Currently, it is set to:

```
./mvnw -e -q compile exec:java
```

This fails on Windows due to the forward slash.

If I run a brand new cdk init app --language=java on a Windows machine the cdk.json file is set to:

```
mvn -e -q compile exec:java
```

Propose updating the default to support Windows, Mac and Linux.