Support duplicated mode in DynamicFragment

[acezen]

What do these changes do?

• add a new loading graph mode which every worker duplicated load the whole graph.
• make duplicated load graph mode as default of networkx.
• use num_workers=2 in nx test

DynamicFragment now support two type of graph storage mode.

• distributed mode: the storage is like other Fragments that every fragment holds a part of graph.
• duplicated mode: every fragment holds the whole graph which duplicated in workers (the mode is designed for APSP-like algorithms and default in networkx).

if users want to use distributed mode to load graph, just init graph by

G = nx.Graph(dist=True)

Related issue number

#317

TODO:

• pass the test case for default duplicated load.
• add new test case to check the add/delete/update is correct on all workers. (move to Add closeness_centrality app and test case of duplicated mode modification #336 )

[yecol]

maybe revise the parameter name.

G = nx.Graph(duplicated_load=True)

[codecov-commenter]

Codecov Report

Merging #325 (88c903a) into main (1e6427e) will decrease coverage by 0.01%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             main     #325      +/-   ##
==========================================
- Coverage   77.37%   77.36%   -0.02%     
==========================================
  Files          57       57              
  Lines        5300     5301       +1     
==========================================
  Hits         4101     4101              
- Misses       1199     1200       +1     

Impacted Files	Coverage Δ
python/graphscope/framework/dag_utils.py	59.56% <0.00%> (-0.27%)	⬇️

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[yecol]

according to our discussion:

# by default, duplicated load
G = nx.Graph()

# or load a fragment, rather than a whole graph.
G = nx.Graph(dist=True)

[acezen]

hi, @yecol @sighingnow @pwrliang the refactoring of duplicated load of DynamicFragment is done. the pr needs you to review again. Thanks a lot.