GitLab

* initial ddpm

for issue #293

* initial ddpm pipeline doc

* added docstrings

* Update docs/source/api/pipelines/ddpm.mdx
Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>

* make style

* fix docs

* make style

* fix doc strings
Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>