Define table schema for vpts

[peterdesmet]

After discussion with @adokter.

• Similar to as.data.frame() output: https://adriaandokter.com/bioRad/reference/as.data.frame.vp.html
• Will not include geo properties (lat, lon, height_antenna): those will be stored in metadata and are same for each record
• Will not include suntime properties (day, sunrise, sunset): those are derived data that can be easily calculated
• Can include u_wind and v_wind: those are sometimes hard to obtain/calculate and avoids a lot of work if these are included
• Can include vcp (volume coverage pattern): with code (or foreignKey) to information about this
• Can include processing: a code (or foreignKey) to the processing settings used (often the same for all records)

[peterdesmet]

This is done in https://github.com/enram/vpts/blob/main/table-schemas/vpts.json