Find run timestamps for runs with voview files

[JamesWrigley]

There are currently two ways to find the timestamp of the start of the run:

• Use run.train_timestamps()
• As a fallback for older runs that don't contain the train timestamps, use the creation timestamp of the RAW files

This is the code for the fallback:

DAMNIT/damnit/ctxsupport/ctxrunner.py

Line 175 in 9c3968a

if np.isnan(ts):

The problem occurs when an old run (without timestamps from the DAQ) is opened using a voview file, because then run.files will only contain that file, which will be ignored by DAMNIT because it's not in the raw/ directory, so the indexing on line 179 will fail. I think it's safe to assume that there'll always be at least one file behind a DataCollection, so maybe if only a voview file is present we should look at the files in the raw/ directory ourselves. Alternatively we could follow the links in the voview file but that seems a bit complicated given that we can fairly easily find the proposal directory.

Maybe in the future we can get the timestamps from mymdc.