Generate getting started template Java as zip

[gvdongen]

We need a getting started Java template. We can use the examples/jvm/java-blocking-http template for this.

To get started a user would need to clone only the examples/jvm/java-blocking-http directory. With git sparse checkout this is possible but it quite verbose (4 commands) and is still evolving so it will depend on the git version a user has....

Instead, we could generate a zip file of this template on each release, that can be downloaded with wget and extracted locally.

[slinkydeveloper]

Done