*-egomotion.csv is a human-readable output file for Calc analysis, not
a machine input source.  *-INTERFRAME.corr-xml is the internal state
always present alongside processed data and is the correct programmatic
source for x/y/z/a/t/r poses.

- remove parse_egomotion_csv() and --ego argument
- --xml is now required
- remove IMS/PIMU col_specs (not in XML)
- rename CSV output columns: ego_* → xml_*, ers_*_rad → xml_*_rad
Co-authored-by: Claude <claude@elphel.com>