`filewriter`: dynamic metadata

[Tom-Willemsen]

The filewriter must be able to write the 'dynamic' metadata for a run.

These are pieces of metadata which require knowledge from the _events stream to compute.

This includes:

• raw_data_1/collection_time (because collection_time excludes vetoed/paused time)
• raw_data_1/framelog/events_log
• raw_data_1/framelog/frame_log
• raw_data_1/framelog/good_frame_log
• raw_data_1/framelog/period_log
• raw_data_1/framelog/proton_charge
• raw_data_1/framelog/raw_events_log
• raw_data_1/good_frames
• raw_data_1/proton_charge
• raw_data_1/proton_charge_raw
• raw_data_1/raw_frames
• raw_data_1/runlog/count_rate
• raw_data_1/runlog/dae_beam_current
• raw_data_1/runlog/good_frames
• raw_data_1/runlog/good_uah_log
• raw_data_1/runlog/is_running
• raw_data_1/runlog/is_waiting
• raw_data_1/runlog/monitor_sum_1
• raw_data_1/runlog/np_ratio
• raw_data_1/runlog/period
• raw_data_1/runlog/period_change_log
• raw_data_1/runlog/raw_frames
• raw_data_1/runlog/raw_uah_log
• raw_data_1/runlog/run_status
• raw_data_1/runlog/total_counts
• raw_data_1/runlog/veto_log
• raw_data_1/total_counts
• raw_data_1/total_uncounted_counts

Potential differences from existing files

• raw_data_1/total_uncounted_counts - "uncounted count" may not be a valid concept in datastreaming world. But we can write it as a constant zero instead.