Add blocks to reference nodes in the scene

https://phabricator.endlessm.com/T35497

Author: dylanmccall

addons/block_code/ui/picker/categories/category_factory.gd

@@ -178,6 +178,18 @@ static func get_general_categories() -> Array[BlockCategory]:
 	# Objects & Types
 	var type_list: Array[Block] = []
 
+	b = BLOCKS["parameter_block"].instantiate()
+	b.block_type = Types.BlockType.NODE
+	b.block_format = "This object"
+	b.statement = 'self'
+	type_list.append(b)
+
+	b = BLOCKS["parameter_block"].instantiate()
+	b.block_type = Types.BlockType.NODE
+	b.block_format = "%{name: STRING}"
+	b.statement = '%{name}'
+	type_list.append(b)
+
 	b = BLOCKS["parameter_block"].instantiate()
 	b.block_type = Types.BlockType.STRING
 	b.block_format = "As String {value: VARIANT}"