*-ims.corr-xml in the scene root dir always has an INS-fused GPS fix
(did_ins_2-lla, fallback did_gps1_pos-lla) giving the representative
position of the sequence for map location.

Changes:
- find_xml_files: also yields ims_path (*-ims.corr-xml from scene root)
- parse_lla(): reads lat/lon from INS or GPS1 LLA entry
- lat/lon added to metrics, console tables, and TSV output
Co-authored-by: Claude <claude@elphel.com>