feat(importers): Add diffuser backend importer with ginkgo tests and UI support (#7316)

* Initial plan

* Add diffuser backend importer with ginkgo tests

Co-authored-by: mudler <2420543+mudler@users.noreply.github.com>

* Finalize diffuser backend importer implementation

Co-authored-by: mudler <2420543+mudler@users.noreply.github.com>

* Add diffuser preferences to model-editor import section

Co-authored-by: mudler <2420543+mudler@users.noreply.github.com>

* Use gopkg.in/yaml.v3 for consistency in diffuser importer

Co-authored-by: mudler <2420543+mudler@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: mudler <2420543+mudler@users.noreply.github.com>