We should be able to override Waveform Generation with specific channels

[Poofjunior]

This is useful for live viewing.

High level, we want to be able to have a live view of a specific channel where the NI card only plays a specific channel. By default, the WaveformGenerator only takes channel specifications from the config. We want to be able to override this (sometimes) to put the NI card in a state where it's playing waveforms only for the specified channel.

old:

def generate_waveforms(cfg, plot: bool = False):
    pass  # stuff here.

new:

def generate_waveforms(cfg, plot: bool = False, channels: list[int] = None):
    pass  # stuff here.