Add leaf module code example (#72100)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/72100
Facebook :
enable splitter to properly read the leaf module specified by acc_tracer leaf module list, and parse leaf module as run_on_acc if customize leaf module converter is provided.
add scratch board for customize leaf module converter and example code for std_conv2d_same converter.
Reviewed By: jfix71
Differential Revision: D33698402
fbshipit-source-id: 01ce84ee1543f0fb8a8899256530ef1300797417
(cherry picked from commit 1357b2d528358da74609b728bfcbe2b8b4b90a50)
