StagingBuff: support both Mlock & IOUring pin; Use in IoUAssmEngn

We use io_uring_register_buffers() for IoUringAssemblyEngine instead
of using mlock(). This __appears__ to have reduced CPU utilization on
the Dell laptop. Could also be that we recently upgraded total RAM
from 8GiB to 32GiB.

stimBuffApis/livoxGen1/ioUringAssemblyEngine.h

@@ -21,6 +21,7 @@
 #include <spinscale/callback.h>
 #include <spinscale/spinLock.h>
 #include <user/frameAssemblyDesc.h>
+#include <user/stagingBuffer.h>
 
 #define IOURINGASSM_ENGN_FRAME_ASSEM_TIMEOUT_MS		\
 	(CONFIG_STIMBUFF_FRAME_PERIOD_MS / 2)
@@ -73,6 +74,7 @@ private:
 	uint64_t eventfd_value;  // Buffer for async_read_some
 	// Point cloud data socket descriptor
 	std::shared_ptr<boost::asio::posix::stream_descriptor> pcloudDataFdDesc;
+	std::unique_ptr<StagingBuffer::IoUringPinner> assemblyBufferIoUringPinner;
 
 	// Stall detection timer
 	boost::asio::deadline_timer stallTimer;
@@ -122,4 +124,3 @@ public:
 
 #endif // _LIVOX_GEN1_IOURING_ASSEMBLY_ENGINE_H
 
-