create Struct for holding data about origin point with method to create custom Spatial Reference (CRS) from this origin, and with methods (or, for now, placeholders) to get origin data from other host apps (e.g. Revit)
Add "Incoming Spatial Reference" to Context Stack (and use it in GIS and non-GIS Receive conversions), so that all scaling/transforms is done in the units and CRS of the incoming data, and saved into a dataset in the original CRS (which might be different from Map settings)
UPD: closeing, will be replaced with OffsetsPR
DO NOT MERGE until https://github.com/specklesystems/speckle-sharp/pull/3521 is merged, and IncomeSpatialReference is applied to those conversions too.