NR_SUBFLOW_NAME returns blank string if the instance name is empty.
This is quite inconvenient and encourages drift as it requires one to set a subflow property manually to the same name as the template if a dev wants to use the subflow's name somewhere but doesn't want to have to define a name for every single instance of it. The flow name is exposed to runtime, so this is a hole in functionality imo. My system tracks runs through various subflows and having to define a subflow property manually mirroring the subflow template name introduces desynchronization risk between the strings used.
FR: Introduce built-in subflow property NR_SUBFLOW_TEMPLATE_NAME (or some other property name as determined by the dev).
What I actually need is a "currently active subflow name" (instance, or if none, then template), but given that NR_SUBFLOW_NAME strictly returns the instance name, it seems cleaner simply to introduce a new, discrete default subflow property in Node-RED.
