Gradient notebook (#1053)

* Update qgans_for_loading_random_distributions.ipynb

* move qGAN tutorial from legacy_tutorials to tutorials

* Update qgans_for_loading_random_distributions.ipynb

* Remove Torch import

* change Kernel

* Update qgans_for_loading_random_distributions.ipynb

* include gradient module tutorial

* update naming -> gradient framework

* update gradient tutorial

* update gradient framework, delete black picture

* fix typos

* Update 02_gradients_framework.ipynb

- minor fixes
- rename to `02_gradients...` to prepare for `01_operator_flow...`

* use circuit instead of circuitfactory

* Update 02_gradients_framework.ipynb

Co-authored-by: Paul Nation <nonhermitian@gmail.com>
Co-authored-by: Cryoris <jules.gacon@googlemail.com>
Co-authored-by: Stefan Woerner <WOR@zurich.ibm.com>

Author: 4 people