Improves performance in workloads that create small opencl buffers.
To enable, set env var ExperimentalSmallBufferPoolAllocator=1
Known issues (will be addressed in further commits):
- cannot create subBuffer from such buffer
- pool buffer allocation should be reused
Related-To: NEO-7332
Signed-off-by: Dominik Dabek <dominik.dabek@intel.com>