[enh] Use lombok for beans (getter/setter and builder, and log)

[enh] use a new Converter interface, for compatibility with Spring-data (need by Cesium+ Pod v2)
[enh] Use a new CrudRepository, for compatibility with Spring-data (need by Cesium+ Pod v2)
[enh] Remove DataContext.accountId
[enh] Add DividendService and repository