geojson: consider configurable serialization

[sargunv]

The specification says:

The size of a GeoJSON text in bytes is a major interoperability
consideration, and precision of coordinate values has a large impact
on the size of texts. A GeoJSON text containing many detailed
Polygons can be inflated almost by a factor of two by increasing
coordinate precision from 6 to 15 decimal places. For geographic
coordinates with units of degrees, 6 decimal places (a default common
in, e.g., sprintf) amounts to about 10 centimeters, a precision well
within that of current GPS systems. Implementations should consider
the cost of using a greater precision than necessary.

Things to investigate:

• Does kotlinx-serialization let us control the precision of Double serialization?
  • Yes, but only with a custom serializer for the field
• Does it make sense to expose some configurable serialization (class GeoJson instead of object GeoJson)? Other than coordinate precision, I could see this being used to:
  • register additional default serializers for feature properties
  • configure strictness of coordinate validate (allow / disallow invalid latlon)
  • configure whether foreign keys are allowed, etc.
  • allow lenient json (comments, trailing comma, Infinity, NaN)