feat: export(block=True) will block next cell execution until export …

[maartenbreddels]

Description

This allows blocking a call, while still responding to widgets, which is useful for exporting figures, e.g.:

exp_plg = cubeviz.plugins['Export']
slice_plg = cubeviz.plugins['Slice']
# for wave in (6.0, 6.1, 6.2):
for wave in (5.5e-7, 7.0e-7, 1e-6):
    slice_plg.value = wave
    for viewer in exp_plg.viewer.choices:#[1:2]:
        exp_plg.viewer = viewer
        exp_plg.filename = f"export/slice_{wave}_{viewer}.png"
        print("saving to", exp_plg.filename)
        exp_plg.export(overwrite=True)#, block=True)

This requires an optional dependency on jupyter_ui_poll

If block=True is not passed, an error will be shown