Implementation of Wishart distribution (#68588)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/68050
TODO:
- [x] Unit Test
- [x] Documentation
- [x] Change constraint of matrix variables with 'torch.distributions.constraints.symmetric' if it is reviewed and merged. https://github.com/pytorch/pytorch/issues/68720
Pull Request resolved: https://github.com/pytorch/pytorch/pull/68588
Reviewed By: bdhirsh
Differential Revision: D33246843
Pulled By: neerajprad
fbshipit-source-id: 825fcddf478555235e7a66de0c18368c41e935cd
