XRADIO Check Schema Implementation

[Jan-Willem]

Ensure that the schema in the spreadsheet (MSv4) matches the XRADIO implementation and the schema checker.

MSv4 Schema: https://docs.google.com/spreadsheets/d/1KIaYp6Qru1appToleyVqRdOEy9hmPhirpg0yR3ovAx0/edit?usp=sharing

• main_xds (int and sd) (conversion+schema seem now in sync with spreadsheet as of 2024/09/12)
• observation_info (added to conversion, mandatory in schema checker) - conversion+schema synced with spreadsheet as of 2024/09/12
• partition_info - conversion+schema synced with spreadsheet as of 2024/09/12
• processor_info (added to conversion, mandatory in schema checker) - conversion+schema synced with spreadsheet as of 2024/09/12
• field_and_source_xds (conversion+schema seem now in sync with spreadsheet as of 2024/09/12)
  Antenna based:
• antenna_xds (seems synced, some comment in spreadsheet - 2024/09/13)
• pointing_xds (conversion+schema seem now in sync with spreadsheet as of 2024/09/13)
• gain_curve_xds (seems synced, some comment in spreadsheet - 2024/09/13)
• phase_cal_xds (seems synced, some comment in spreadsheet - 2024/09/13)
• system_calibration_xds (conversion+schema seem now in sync with spreadsheet as of 2024/09/13)
• weather_xds (conversion+schema seem now in sync with spreadsheet as of 2024/09/13)
• phased_array_xds (skip)

[FedeMPouzols]

This branch has now an updated version that brings the schema classes and the conversion code up to date with the spreadsheet:

• There were a few comments open throughout the day, mostly about coordinates in gain_curve_xds, phase_calibration_xds, antenna_xds. But I think most if not all are now clear
• The type attribute in the datasets, which @scpmw introduced I think, and I've been keeping and extending to new sub-datasets, is not in the spreadsheet.

Other than that I do not see other differences at the moment. If a few last checks on the current branch go well, I'll open a PR. If some adjustments are needed, those should be pretty small, so the disruptive changes of names that need to be done can start sooner than later.