libcamera: yaml_parser: Add functions to add children

Add YamlObject::add() functions to add children to a list or dictionary
object. This will be used by the YamlParserContext to replace direct
access to YamlObject member variables to decouple the two classes.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Isaac Scott <isaac.scott@ideasonboard.com>
Reviewed-by: Barnabás Pőcze <barnabas.pocze@ideasonboard.com>

include/libcamera/internal/yaml_parser.h

@@ -28,7 +28,7 @@ class YamlObject
 {
 private:
 	struct Value {
-		Value(std::string &&k, std::unique_ptr<YamlObject> &&v)
+		Value(std::string k, std::unique_ptr<YamlObject> &&v)
 			: key(std::move(k)), value(std::move(v))
 		{
 		}
@@ -197,6 +197,9 @@ public:
 	bool contains(std::string_view key) const;
 	const YamlObject &operator[](std::string_view key) const;
 
+	YamlObject *add(std::unique_ptr<YamlObject> &&child);
+	YamlObject *add(std::string key, std::unique_ptr<YamlObject> &&child);
+
 private:
 	LIBCAMERA_DISABLE_COPY_AND_MOVE(YamlObject)