[feat]Rocksdb backend

[bashimao]

RocksDB backend for TFRA Hastabale.

[rhdong]

Hi @bashimao , thank you for your contribution , and can you squash your commits to one and describe your feature detail in your comment?

[bashimao]

@rhdong What could case this? @MoFHeka

root@13beb51e47e9:/# python
Python 3.7.7 (default, Jan 19 2022, 04:18:49) 
[GCC 7.5.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from tensorflow_recommenders_addons import dynamic_embedding as de
2022-03-27 20:28:04.992289: I tensorflow/stream_executor/platform/default/dso_loader.cc:53] Successfully opened dynamic library libcudart.so.11.0
WARNING:tensorflow:dynamic_embedding.GraphKeys has already been deprecated. The Variable will not be added to collections because it does not actully own any value, but only a holder of tables, which may lead to import_meta_graph failed since non-valued object has been added to collection. If you need to use `tf.compat.v1.train.Saver` and access all Variables from collection, you could manually add it to the collection by tf.compat.v1.add_to_collections(names, var) instead.
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python3.7/site-packages/tensorflow_recommenders_addons/__init__.py", line 29, in <module>
    from tensorflow_recommenders_addons import dynamic_embedding
  File "/usr/local/lib/python3.7/site-packages/tensorflow_recommenders_addons/dynamic_embedding/__init__.py", line 58, in <module>
    from tensorflow_recommenders_addons.dynamic_embedding.python.ops.cuckoo_hashtable_ops import (
  File "/usr/local/lib/python3.7/site-packages/tensorflow_recommenders_addons/dynamic_embedding/python/ops/cuckoo_hashtable_ops.py", line 33, in <module>
    cuckoo_ops = LazySO("dynamic_embedding/core/_cuckoo_hashtable_ops.so").ops
  File "/usr/local/lib/python3.7/site-packages/tensorflow_recommenders_addons/utils/resource_loader.py", line 102, in ops
    self._ops = tf.load_op_library(get_path_to_datafile(self.relative_path))
  File "/usr/local/lib/python3.7/site-packages/tensorflow/python/framework/load_library.py", line 58, in load_op_library
    lib_handle = py_tf.TF_LoadLibrary(library_filename)
tensorflow.python.framework.errors_impl.NotFoundError: /usr/local/lib/python3.7/site-packages/tensorflow_recommenders_addons/dynamic_embedding/core/_cuckoo_hashtable_ops.so: undefined symbol: _ZN10tensorflow14kernel_factory17OpKernelRegistrar12InitInternalEPKNS_9KernelDefEN4absl12lts_2021032411string_viewESt10unique_ptrINS0_15OpKernelFactoryESt14default_deleteIS9_EE

[rhdong]

Just remove the block