[ADD] Extraction shaded region to raw extraction

[singjc]

Add extraction shaded box to show extraction windows, similar to skyline.

Add an optional extra amount to extraction windows of data to extract for this to make sense/usability. Current extraction, extracts data with the exact windows.

Can add bands to bokeh plot using something like below.

p.xgrid.band_fill_color = "olive"
p.xgrid.band_fill_alpha = 0.1