Automatically run "connect" command after opening spectrometer devices

[alexdewar]

(NB: In this case, "connect" refers to the connection between the external software and the spectrometer, not the one between FINESSE and the external software!)

It would be useful to automatically initiate the connection after spectrometer devices are opened. Depending on the device, it may require checking that the device isn't already connected before doing this in order to avoid getting an error message.

[alexdewar]

It doesn't make sense to start this until after #638 and we can open the various spectrometers asynchronously (particularly the EM27).