Scripting Fields API X-Pack Version should implement Comparable<Version>

The `Version` value class of the fields API should implement `Comparable<Version>` based on the implementation of [`VersionEncoder.EncodedVersion`](https://github.com/elastic/elasticsearch/blob/master/x-pack/plugin/mapper-version/src/main/java/org/elasticsearch/xpack/versionfield/VersionEncoder.java#L178).

This will allow users to naturally sort that value class.