Progress printing should be cli specific

[hardbyte]

Assuming clk.py is meant to be common code that could support a number of different interfaces, then tqdm’s progress bars (which are specific to a CLI) should be handled in cli rather than clk - perhaps by passing a progress-bar callback to clk rather than a “progress_bar” boolean. (Or, could at least reduce code duplication by having only one call to generate_clks, with callback=None if no progress_bar.)

Aha! Link: https://csiro.aha.io/features/ANONLINK-38