libcamera can detect camera transforms/rotation, e.g. from the device
tree, and makes that information usable for clients via
`CameraConfiguration::transform`.
Advertise this information via the VideoTransform meta so Pipewire
clients can adjust their output accordingly.
Rotated cameras are common in mobile devices such as the Pinephone Pro,
which was used to test this feature.
Pick the first format in the list of supported as something closest
to 640x480 instead of the lowest possible resolution.
Applications that don't suggest a default size will then get something
more sensible than a poster frame.
Keep track of the negotiated parameters and use those to construct
the Buffers param.
Use the FrameAllocator to allocate buffer memory. Keep a request for
each buffer and queue them.
In requestComplete, put the request metadata info into the buffer and
header and write the finished buffer id to a ringbuffer. Then wake up
the data thread to pop the finished buffer_id and push it in the
graph.
Remove some old files.
