libcamera: Improve Request life cycle tracking

The current logging to track the status of a Request when running the
Android camera HAL provide the following information:

When a Request is queued to libcamera:
HAL camera_device.cpp:1776 '\_SB_.PCI0.I2C2.CAM0': Queueing Request to libcamera with 1 HAL streams

When a Request completes:
Request request.cpp:268 Request has completed - cookie: 138508601719648

The queueing of a Request reports the number of streams it contains
while the completion of a Request reports the address of the associated
cookie.

This makes very hard to keep track of what Requests have completed, as
the logging associated with a queue/complete event does not allow to identify
a Request easily.

Add two more printouts to make it easier to track a Request life cycle.
To make it possible to print the Request cookie in the CameraDevice
class add a method to access it from the CameraRequest class.

The result looks like the following trace:

Request request.cpp:92 Created request - cookie: 140701719392768
HAL camera_device.cpp:1710 '\_SB_.PCI0.I2C2.CAM0': Queueing request 140701719392768 with 1 streams
HAL camera_device.cpp:1747 '\_SB_.PCI0.I2C2.CAM0': 0 - (4160x3104)[0x00000023] -> (4160x3104)[NV12] (direct)
...
Request request.cpp:268 Request has completed - cookie: 140701719392768
HAL camera_device.cpp:1800 '\_SB_.PCI0.I2C2.CAM0': Request 140701719392768 completed with 1 streams..

Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>

src/android/camera_worker.h

@@ -30,6 +30,7 @@ public:
 	{
 		return request_->metadata();
 	}
+	unsigned long cookie() const { return request_->cookie(); }
 
 	void addBuffer(libcamera::Stream *stream,
 		       libcamera::FrameBuffer *buffer, int fence);