Unify the XML parsing of GEOS files

[alexbenedicto]

As discussed with @mlemayTTE , 3 different methods are used to parse GEOS xml files and are defined in different packages (geos-xml-tools, geos-xml-viewer, pygeos-tools).

Tasks:

• Unify these 3 different methods into a single one and store it into the geos-xml-tools.
• Cleanup the packages using the XML parsing.