Download lutra-stottr JAR file with all dependencies

This Lutra submodule implements readers and writers for the stOTTR formalisation format (https://spec.ottr.xyz/stOTTR/). stOTTR is a custom-built serialisation format for OTTR intended to be easy to read and write for humans (and computers!). Lutra is the reference implementation of the OTTR framework. For more information about OTTR, see http://ottr.xyz.