Live stream images should come from Instrument

[adamkglaser]

Is your feature request related to a problem? Please describe.
Currently, the live streaming logic is happening here

exaspim-control/exaspim_control/experimental/exa_spim_view.py

Lines 30 to 47 in c622c17

	@thread_worker
	def grab_frames(self, camera_name, frames=float("inf")):
	"""Grab frames from camera and create multiscale array
	:param frames: how many frames to take
	:param camera_name: name of camera"""
	i = 0
	while i < frames: # while loop since frames can == inf
	with self.camera_locks[camera_name]:
	frame = self.instrument.cameras[camera_name].grab_frame()
	# TODO: Do we want to import from exaspim what to use?
	multiscale = [frame]
	for binning in range(2,6): # TODO: variable or get from somewhere?
	downsampled_frame = DownSample2D(binning=binning).run(frame)
	multiscale.append(downsampled_frame)
	yield multiscale, camera_name # wait until unlocking camera to be able to quit napari thread
	i += 1

.

Describe the solution you'd like
This should ideally be moved into the instrument and out of the view.

Acceptance Criteria

• Moved from view to instrument and unit tested to be working