[HGLDD] Uniquify object names during emission

[Fabian Schuiki]

Make HGLDD emission add some form of uniquification suffix to objects with duplicate names. Right now, if there are two debug variables with the same name, the emitter will happily include both with the same name. This is likely to crash in the tool that ingests the debug information (some may materialize the debug variables as Verilog XMRs or similar kinds of "views").

Also prevent empty names from being printed.