Initial implementation for JSONFG output format

[nls-jajuko]

hakunapi-jsonfg module

First steps to support JSON-FG https://docs.ogc.org/DRAFTS/21-045.html

[nls-jajuko]

Some notes, questions and todos:

• "featureSchema": Should find a way to support describedBy links to JSON-FG schemas as well as schema output for JSON-FG schemas. This might require json-schema factory of some sort for similar formats
• "geometry" is reprojected within output format writer
• "place" is output as is
• "time" support does not work with possibly multiple datetime properties - maybe there should be some configurable options for this

[jampukka]

"geometry" is reprojected within output format writer

I'm thinking we should probably add a default function to either HakunaFeature or HakunaGeometry which would provide the "lesser geometry" to be used as the value for geometry (like a simplified footprint or centroid of a building). The default implementation would return the actual geometry as-is, but we could expand on that so that sources could provide simplified CRS84-ready versions of the geometry.

[nls-jajuko]

https://github.com/nlsfi/hakunapi/blob/main/src/hakunapi-simple-servlet-javax/src/main/java/fi/nls/hakunapi/simple/servlet/javax/GlobalFQueryParamFilter.java

I think GlobalFQueryParamFilter clashes with custom output formats

[jampukka]

Looks good to me. An example json which unit tests would match against would've been great but not necessary.

[nls-jajuko]

first steps towards validating JSONFG output - should find out a source for the jsonfg json-schemas https://docs.ogc.org/DRAFTS/21-045.html#schema-feature-collection some schemas https://beta.schemas.opengis.net/json-fg/

[nls-jajuko]

Added a generic validation test for feature collection writer