Move relational schema configuration into RelationalSchemaConfig class
OFC-1323 - Add configuration to exporter for default code and default
code label
OFC-1324 When exporting, insert default code insert code list table if
it doesn't already exist
OFC-1325 - When exporting, replace null codes with default value if provided
OFC-1329 - Merge DatabaseExporterConfig and RelationalSchemaConfig into
unique config class

Code clean, renamed classes