improve ICA latent source viz in Reports

[drammock]

I have more than 20 Independent Components, but for the moment I can just have a look to the first 20s of the first 20 ICs [in the report]. This is why for the moment I have to use a .ipynb in parallel to the html report.

For making batch processing faster, it would be great to be able to scroll through all ICs (and maybe use the same logic as in butterfly in mne.Report.add_raw() to select how many 20s windows to plot).

I imagine different 20 ICs subplots to span all the ICs present, or having the desired number of 20s snapshots of each IC timecourse piled under its corresponding ica.plot_properties() plot.

Originally posted by @LeonardoMelloni in #13265

For whoever takes this on: 20 is currently hard-coded here:

mne-python/mne/viz/ica.py

Line 1351 in 893b784

n_channels = min([20, len(picks)])