Created by: zhhsplendid

This PR does exact the thing as the title. The reason is that we plan to develop 4 decorators

"dygraph_to_static_code" "dygraph_to_static_program" "dygraph_to_static_func" "dygraph_to_static_output"

The 4 decorators will emphasize different part when translating dygraph to static graph. Decorator name "dygraph_to_static_graph" is too big for the function it implements.