JSON support for changeset upload

[mmd-osm]

Back in openstreetmap/openstreetmap-website#3501 we've talked about adding JSON support for a few remaining endpoints. Unfortunately, this project never took off. Why not give it another try now.

I found a streaming json parser based on yajl called sjparser, that has schema support. It offers a much saner interface than yajl alone, and emits one OSM element at a time. It also hides all that ugly state handling, unlike the XML parser we have in place today.

• Define new format specifications for JSON based messages:
  • /api/0.6/changeset/nnn/upload
    • Input: OSMChange, based on OSM JSON format -> some examples in test_parse_osmchange_json_input.cpp
    • Output: diffResult: TODO

There are a few other changeset related endpoints (create / update) that don't support JSON. This can be addressed in another PR. Single object edit operations will continue be out of scope for this repo.

[mmd-osm]

Created some issues for sjparser:

• https://gitlab.com/dhurum/sjparser/-/issues/1
• https://gitlab.com/dhurum/sjparser/-/issues/2

[mmd-osm]

{
	"version": "0.6",
	"generator": "demo",
	"osmChange": [
		{
			"type": "node",
			"action": "create",
			"id": -1,
			"lat": 81.0714,
			"lon": -139.0956,
			"changeset": 159556552,
			"tags": {
				"man_made": "mast",
				"name": "Principal"
			}
		},
		{
			"type": "node",
			"action": "modify",
			"id": 12394725038,
			"version": 3,
			"lat": -50.2701,
			"lon": 131.176,
			"changeset": 159556552,
			"tags": {
				"man_made": "mast",
				"name": "Future"
			}
		},	
		{
			"type": "relation",
			"action": "delete",
			"id": 18320662,
			"version": 1,
			"changeset": 159556552
		},				
		{
			"type": "way",
			"action": "delete",
			"id": 1338869356,
			"version": 1,
			"changeset": 159556552
		},			
		{
			"type": "node",
			"action": "delete",
			"id": 12394725046,
			"version": 1,
			"changeset": 159556552
		},			
		{
			"type": "node",
			"action": "create",
			"id": -2,
			"lat": 42.03321443,
			"lon": 13.5690032,
			"changeset": 159556552,
			"tags": {
				"man_made": "mast",
				"name": "Monte Piselli - San Giacomo"
			}
		},
		{
			"type": "node",
			"action": "create",
			"id": -3,
			"lat": 41.03321443,
			"lon": 11.5690032,
			"changeset": 159556552,
			"tags": {
				"man_made": "mast",
				"name": "Monte Piselli - San Giacomo"
			}
		},
		{
			"type": "way",
			"action": "create",
			"id": -1,
			"changeset": 159556552,
			"nodes": [
				-1,
				-2,
				-3,
				-1
			],
			"tags": {
				"man_made": "mast",
				"name": "Monte Piselli - San Giacomo"
			}
		},
		{
			"type": "relation",
			"action": "create",
			"id": -1,
			"changeset": 159556552,
			"members": [
				{
					"type": "Node",
					"ref": -1,
					"role": "stop"
				},
				{
					"type": "Way",
					"ref": -1
				}
			],
			"tags": {
				"boundary": "administrative",
				"name": "Admin boundary"
			}
		}
	]
}

{
	"version": "0.6",
	"generator": "openstreetmap-cgimap 2.0.1.2503291758 (14989 ubuntu)",
	"copyright": "OpenStreetMap and contributors",
	"attribution": "http://www.openstreetmap.org/copyright",
	"license": "http://opendatacommons.org/licenses/odbl/1-0/",
	"diffResult": [
		{
			"type": "node",
			"old_id": -1,
			"new_id": 12394725050,
			"new_version": 1
		},
		{
			"type": "node",
			"old_id": 12394725038,
			"new_id": 12394725038,
			"new_version": 4
		},
		{
			"type": "relation",
			"old_id": 18320662
		},
		{
			"type": "way",
			"old_id": 1338869356
		},
		{
			"type": "node",
			"old_id": 12394725046
		},
		{
			"type": "node",
			"old_id": -2,
			"new_id": 12394725051,
			"new_version": 1
		},
		{
			"type": "node",
			"old_id": -3,
			"new_id": 12394725052,
			"new_version": 1
		},
		{
			"type": "way",
			"old_id": -1,
			"new_id": 1338869357,
			"new_version": 1
		},
		{
			"type": "relation",
			"old_id": -1,
			"new_id": 18320663,
			"new_version": 1
		}
	]
}