Isolate `examples` module in build configuration

[laszlourszuly]

As is now, the radixdlt-java repository holds two Gradle modules; the actual Radix Java Library and a set of Example implementations. Both modules are built or at least verified when the deliverable is assembled (though the examples module isn't actually included in the artefact).

We are exposing the product to unnecessary risks with the current build configuration, while the examples module has its own set of (third party) dependencies that can brake (we've actually already seen this in the JitPack release, version 0.11.5).