cqlgen should generate compliant identifiers without hyphens

[jshook]

While the rest of the nb5 codebase has been modified to avoid using hyphens where identifiers may be generated, cqlgen has not. cqlgen templates need to be updated to use underscores by default.

All of this should be easily configurable from nb-adapters/adapter-cqld4/src/main/resources/cqlgen/cqlgen.conf, and a basic test can be run to verify that no hyphens are used in the generated workload.