Digital RF Copy command (ilsdrf) should skip directories with no data

[rherban]

If a directory only has properties files or just metadata, skip it.

Channels B, C & D below should be skipped:

./chD
./chD/metadata
./chD/metadata/dmd_properties.h5
./chD/metadata/2016-07-26T21-00-00
./chD/metadata/2016-07-26T21-00-00/metadata@1469569992.h5
./chD/drf_properties.h5
./chC
./chC/metadata
./chC/metadata/dmd_properties.h5
./chC/metadata/2016-08-07T16-00-00
./chC/metadata/2016-08-07T16-00-00/metadata@1470587348.h5
./chC/drf_properties.h5
./chB
./chB/metadata
./chB/metadata/dmd_properties.h5
./chB/metadata/2016-08-07T16-00-00
./chB/metadata/2016-08-07T16-00-00/metadata@1470587572.h5
./chB/drf_properties.h5
./chA
./chA/metadata
./chA/metadata/dmd_properties.h5
./chA/drf_properties.h5
./chA/2025-12-08T04-00-00
./chA/2025-12-08T04-00-00/rf@1765166406.000.h5
./chA/2025-12-08T04-00-00/rf@1765166405.000.h5
./chA/2025-12-08T04-00-00/rf@1765166407.000.h5
...