Add CODE_BLOCK, STAMP and HIGHLIGHTER nodes to the REST API

Currently the following node types are not included in JSON output: CODE_BLOCK, STAMP, HIGHLIGHTER.

If you use the GET file endpoint, the JSON will not have any of the above nodes.

If you use the GET file nodes endpoint, you will get this output for each of the above nodes:

{
	"document": null,
	"components": {},
	"componentSets": {},
	"schemaVersion": 0,
	"styles": {}
}