add cogdl stgcn code - Githubissues

Description

Please feel free to remove inapplicable items for your PR.

[x] The PR title starts with [$CATEGORY] (such as [Model], [Doc], [Feature], [Bugfix])
[x] Changes are complete (i.e. I finished coding on this PR)
[x] All changes have test coverage
[x] Code is well-documented
[x] To my best knowledge, examples are either not affected by this change, or have been fixed to be compatible with this change
[x] Related issue is referred in this PR