`view`: add `--scalebar-linewidth` option

[yunjunz]

Description of proposed changes

• view: add --scalebar-linewidth option

• prep_gamma: fix the inps.sensor.lower() issue when sensor is not specified, i.e. inps.sensor is None, by shifting the lower() operation inside extract_metadata4interferogram()

• asc_desc2horz_vert.get_design_matrix4east_north_up(): add type checking for the obs_direction arg.

Reminders

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