set the MAIN SYNC parameter from iblrig, in a safe manner

[oliche]

The Slack thread is there: https://int-brain-lab.slack.com/archives/C012URA26TE/p1711100988083029

Thanks Mayo, cross-posting this to the HW channel.
Right now they would have to manually edit the hardware_settings. I did not show them while in Seattle on purpose (sorry).
My fear was that getting MAIN_SYNC wrong for the behaviour has a modest impact, while getting MAIN_SYNC wrong for ephys has a large impact, and I was afraid that the back and forth between Kim's experiments and Matt training would lead to ephys problems.
Right now there is no interface, but we could add a field in the GUI, with a safeguard, options could be either or both of:
if there is ephys in the rig name and MAIN_SYNC is True, throw a confirmation dialog asking to confirm this is a training session
if the ephys protocol is chosen and MAIN_SYNC is True, throw an error dialog preventing the user to go forward