Add --csvStartRow utility as is in BBAA

[Maylor8]

@chanshing Actigraph raw .csv files come with 11 rows of header data. I can easily use "--csvStartRow 12" to skip these in BBAA, but this function does not exist in Stepcount. An example of the fixed header:

---------- Data File Created By ActiGraph LEAP v2 ActiLife v7.0.0 Firmware v2.0.1 date format dd/MM/yyyy at 32 Hz  Filter Normal --------- Serial Number: STM2E24243267 Start Time 17:16:00 Start Date 11/12/2024 Epoch Period (hh:mm:ss) 00:00:00 Download Time 14:52:19 Download Date 16/12/2024 Current Memory Address: 0 Current Battery Voltage: 3.743     Mode = 12

Timestamp | Accelerometer X | Accelerometer Y | Accelerometer Z 11/12/2024 17:41:40.000 | -0.131 | -0.407 | -0.652 11/12/2024 17:41:40.032 | -0.118 | -0.392 | -0.696 11/12/2024 17:41:40.063 | -0.089 | -0.493 | -0.601 11/12/2024 17:41:40.094 | -0.325 | -0.243 | -0.562

Could we get this in StepCount too please?