src: extract backend driver from bluestore to access device

src: extract backend driver from bluestore to access device

1. Both bluestore or other component e.g. rbd could use the same
   driver to access storage device. It's better to use one library
   to integrate the driver.
2. os and crimson-alienstore are static libraries. Link blk library into
   them.

Main changes are below:
1. move backend driver into src/blk
   src/$ mkdir -p blk/{aio,kernel,spdk,pmem,zns}
   src/$ mv os/bluestore/{BlockDevice.h,BlockDevice.cc} blk
   src/$ mv os/bluestore/{ceph_aio.h} aio/aio.h
   src/$ mv os/bluestore/{aio.cc} aio/
   src/$ mv os/bluestore/{KernelDevice.h,KernelDevice.cc} kernel/
   src/$ mv os/bluestore/{ceph_io_uring.h} kernel/io_uring.h
   src/$ mv os/bluestore/{io_uring.cc} kernel_drv/
   src/$ mv os/bluestore/{NVMEDevice.h,NVMEDevice.cc} spdk/
   src/$ mv os/bluestore/{PMEMDevice.h,PMEMDevice.cc} pmem/
   src/$ mv os/bluestore/{HMSMRDevice.h,HMSMRDevice.cc} zns/
2. customize macro name in header file to remove bluestore specific text
3. adjust header file patch in source code
4. create cmake rule blk/CMakeLists.txt to build blk
5. modify src/CMakeLists.txt to integrate blk
6. modify other CMakeLists.txt to adapt to new file structure.

Signed-off-by: Changcheng Liu <changcheng.liu@aliyun.com>
Co-authored-by: Kefu Chai <kefu@redhat.com>