libcamera: converter: Add interface for feature flags

This patch intends to extend the converter interface to have feature
flags, which enables each converter to expose the set of features
it supports.

Signed-off-by: Umang Jain <umang.jain@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/libcamera/converter/converter_v4l2_m2m.cpp

@@ -446,6 +446,10 @@ int V4L2M2MConverter::queueBuffers(FrameBuffer *input,
 	return 0;
 }
 
+/*
+ * \todo: This should be extended to include Feature::Flag to denote
+ * what each converter supports feature-wise.
+ */
 static std::initializer_list<std::string> compatibles = {
 	"mtk-mdp",
 	"pxp",