Missing XA datasources

[mgotovac]

In our projects we frequently rely on XA datasources and I attempted to configure a Galleon layer for a PostgreSQL XA datasource. However, I found the process to be more challenging than expected, primarily due to the lack of documentation on how to properly define XA datasource properties as well as what are the required params within the layer configuration.

I believe that extending the pack to include support for XA datasources (or improving documentation around it) would be a highly valuable enhancement for the community.

Thanks for your work on this project, and happy to help test or contribute if needed!