Use a Telescope object to supply the frequency specification for sims

[jrs65]

From @sjforeman:

One of my pet peeves about cora has always been that the frequencies need to be explicitly specified by the user, and you'll only find out at a later stage if they don't match the telescope object you're using to generate sims. Is it possible to add an option to specify a telescope or ProductManager and have the frequencies pulled directly from there?

It should be possible. One complication is that this would cause a cyclic dependency between cora and driftscan so we'd need to figure that out.