Reorganize examples (#9010)

* Reorganize example folder

* Continue reorganization

* Change requirements for tests

* Final cleanup

* Finish regroup with tests all passing

* Copyright

* Requirements and readme

* Make a full link for the documentation

* Address review comments

* Apply suggestions from code review
Co-authored-by: Lysandre Debut <lysandre@huggingface.co>

* Add symlink

* Reorg again

* Apply suggestions from code review
Co-authored-by: Thomas Wolf <thomwolf@users.noreply.github.com>

* Adapt title

* Update to new strucutre

* Remove test

* Update READMEs
Co-authored-by: Lysandre Debut <lysandre@huggingface.co>
Co-authored-by: Thomas Wolf <thomwolf@users.noreply.github.com>

examples/lxmert/requirements.txt → examples/research_projects/movement-pruning/lxmert/requirements.txt

@@ -90,7 +90,7 @@ torchvision==0.7.0
 tornado==6.0.4
 tqdm==4.48.2
 traitlets
-git+https://github.com/huggingface/transformers.git
+transformers==3.5.1
 urllib3==1.25.8
 wcwidth==0.2.5
 webencodings==0.5.1