[FEA]: Add type-hints for missing modules added in cugraph_dgl package

[VibhuJawa]

Is this a new feature, an improvement, or a change to existing functionality?

Improvement

How would you describe the priority of this feature request

Medium

Please provide a clear description of problem this feature solves

In this PR #2896 we have some missing type hints for dgl.backend and DataFrame specific objects , we should look into a solution for adding those.

Describe your ideal solution

Every-user facing arg should have a type-hints and have everything tested with mypy or a similar type hint checker.

Describe any alternatives you have considered

No response

Additional context

CC: @rlratzel

Code of Conduct

• I agree to follow cuGraph's Code of Conduct
• I have searched the open feature requests and have found no duplicates for this feature request