Print out intial timestamps and counters in nsec instead of seconds

[morcuended]

Since r0_to_dl1 uses timestamps and the corresponding counters in nsec (integers) as input, we should print out those same values in nsecs instead of seconds to avoid confusion.

[morcuended]

This is how it currently looks:

Using first event as time reference for counters, this will lead to wrong timestamps / trigger types for all but the first subrun
Using first event as time reference for dragon. UCTS timestamp: 1582059789516171575 dragon_counter: 2516171300
Using first event as time reference for TIB. UCTS timestamp: 1582059789516171575 tib_counter: 2516170900

[maxnoe]

This is now in ctapipe_io_lst, where a log.critical message has the timestamp values in ns.

However, I think we probably should make a dedicated tool to produce these night summary files, right?

[morcuended]

Closing this. Run summaries are produced now with the script made in #614.