GitLab

* add doc.

* update DistGraph.

* add DistTensor.

* update DistEmbedding.

* add partition.py

* add sampling.

* fix.

* add graph partition book and create a base class.

* fix test.

* add rst.

* update doc rst.

* update.

* fix.

* fix docs

* update distributed tensor and embeddings.

* add checks.

* update DistGraph.

* update initialization.

* fix graph partition book.

* update graph partition book.

* update partition.

* update partition.

* fix.

* add example code.

* update DistGraph

* Update python/dgl/distributed/dist_context.py
Co-authored-by: Quan (Andy) Gan <coin2028@hotmail.com>

* Update python/dgl/distributed/dist_context.py
Co-authored-by: Quan (Andy) Gan <coin2028@hotmail.com>

* Update python/dgl/distributed/dist_dataloader.py
Co-authored-by: Quan (Andy) Gan <coin2028@hotmail.com>

* Update python/dgl/distributed/dist_dataloader.py
Co-authored-by: Quan (Andy) Gan <coin2028@hotmail.com>

* Update python/dgl/distributed/dist_dataloader.py
Co-authored-by: Quan (Andy) Gan <coin2028@hotmail.com>

* update initialize.

* update dataloader.

* update distgraph.

* update DistGraph.

* update DistTensor.

* update.

* more updates.

* fix lint.

* add num_nodes and num_edges
Co-authored-by: Chao Ma <mctt90@gmail.com>
Co-authored-by: Quan (Andy) Gan <coin2028@hotmail.com>
Co-authored-by: xiang song(charlie.song) <classicxsong@gmail.com>