Merge pull request !26570 from petitquentin/Gather_version_update

Merge pull request !26494 from Xiaoda/102-adjusting-sharding-propagation

Merge pull request !26397 from Hongxing/Gather_version_update

Merge pull request !26462 from Xiaoda/104-fix-some-codestyles-on-r1.5

1) when propagate sharding strategy from one op to another, try to find the strategy with zero communication cost;
2) if there is no such strategy, find the strategy with minimum communication cost, and raise a warning;

Merge pull request !26163 from Arthur/Gather_version_update

Merge pull request !26036 from yangzhenzhang/add-output-strategy-for-op-init

1) using 'swc index of strategy_cost_' as reshape's selected strategy;
2) when encountering reshape in BFS, select the 'swc index' with zero communication cost;
3) when encountering a reshape that is already visited, check whether there exists communication between reshape and current operator. It is OK if communication happens between two configured operators;
4) currently, two consecutive reshapes are not supported;
5) adjusting BFS structure in graph_costmodel.cc;
6) adjusting some code in step_auto_parallel.cc to avoid cyclomatic complexity.

Merge pull request !23351 from wangjun/uniformreal_parallel_ops

Merge pull request !23239 from Chong/xtan

Merge pull request !23434 from Chong/PanGu-VirtualDataset

Merge pull request !22970 from Chong/PanGu-Daniel_code

1) users configure sharding strategies for operators;
2) framework will propagate the strategies from configured-ops to
non-configured ops using BFS;
3) the propagation goal is to minimize redistribution communication
cost;

1. Add some const variables to represent the input length of operators,
and use them to eliminate some magic numbers;
2. Rename some local variables to distingush other variables in
different ranges;
3. Add some blank rows in python files.