[uss_qualifier] Parse operator altitude in kml files

[mickmis]

Fix #1445

• only support MSL altitude as this is what we need to output to, and probably don't want to compute elevation in the parsing
• add in two kml files the altitude of the operator (determined manually by checking elevation of coordinates)
• add the requirements (NET0260|NET0470),Table1,(25|26) to relevant requirements and configurations