KML exhausts memory

The MappingServiceImpl#filteredKml is generating the KML in memory and returns a String. This exhausts memory on the server.

Please add a test and allow execution if filters give <= 200,000 records to

1. mappingService.filteredGeoJson

2. mappingService.filteredKml

Throw exception if filter produces over 200,000 records.

Next, convert the filteredGeoJson to accept the response OutputStream and write the KML directly to the response stream, not a String buffer.

Exhausting memory on the server

1. Go to "https://sandbox.genesys-pgr.org/welcome";
2. Click on the map area;
3. Click on the "DOWNLOAD KML" button;
4. On the Download pop-up click "cancel" button;
5. Click on the "DOWNLOAD KML" button again;

The reproducibility of the error is unstable, and it can take several repetitions.