todo: allow all simulation methods to work for all channels

[tlambert03]

currently only Simulation.run() returns all channels, via this code:

microsim/src/microsim/schema/simulation.py

Lines 105 to 114 in 652fc1d

	if channels is None:
	channels = tuple(range(len(self.channels)))
	elif isinstance(channels, int):
	channels = (channels,)
	images = []
	for channel_idx in channels:
	emission_flux = self.emission_flux(truth, channel_idx=channel_idx)
	optical_image = self.optical_image(emission_flux, channel_idx=channel_idx)
	images.append(self.digital_image(optical_image))
	image = xr.concat(images, dim=Axis.C)

but that should be put higher up the chain, allowing someone to request any of emission_flux, optical_image, or digital_image and get the full channels output