libcamera: Use stream roles directly instead of StreamUsage

In order to prepare for an API overhall of the camera configuration
generation, remove the StreamUsage class and replace its uses by stream
roles. The size hints can't be specified anymore, and will be replaced
with an API on the StreamConfiguration to negotiate configuration
parameters with cameras.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>

src/libcamera/include/pipeline_handler.h

@@ -14,6 +14,8 @@
 #include <string>
 #include <vector>
 
+#include <libcamera/stream.h>
+
 namespace libcamera {
 
 class Buffer;
@@ -26,8 +28,6 @@ class DeviceMatch;
 class MediaDevice;
 class PipelineHandler;
 class Request;
-class Stream;
-class StreamUsage;
 
 class CameraData
 {
@@ -61,7 +61,7 @@ public:
 	void unlock();
 
 	virtual CameraConfiguration
-	generateConfiguration(Camera *camera, const std::vector<StreamUsage> &usages) = 0;
+	generateConfiguration(Camera *camera, const StreamRoles &roles) = 0;
 	virtual int configure(Camera *camera, const CameraConfiguration &config) = 0;
 
 	virtual int allocateBuffers(Camera *camera,