Make it easier to launch online monitoring in the middle of a run
After discussion during my presentation of online monitoring at the SBND meeting, it was suggested that it be made simple to launch online monitoring in the middle of a run. This is similar to the spirit of Feature #16615. While there's already the ability to do that without much difficulty (https://cdcvs.fnal.gov/redmine/projects/artdaq-demo/wiki/Running_a_sample_artdaq-demo_system#Monitoring-the-data), since it will likely be done quite often in running experiments it would be ideas to make it even simpler. One possible approach would be to send DAQInterface the name of the FHiCL document to use for online monitoring via XML-RPC, though I haven't yet thought out the implementation details for this.