Code formatting

Context

issue : aidge#6

• Update readme

.gitlab/ci/code_quality/formatting_check.gitlab-ci.yml

+format:check_code:
+  stage: format
+  rules:
+  tags:
+    - docker
+  before_script:
+    - !reference [.retrieve_deps:apt, script]
+    - apt-get install -y git
+    - pip install ruff
+  script: 
+    - echo "Ensuring that all python files modified in previous commit are correctly formatted. If not, this job will fail."
+    - modified_files=$(git merge-base HEAD origin/dev) # change "dev" to $CI_DEFAULT_BRANCH when whole codebase is formatted
+    - modified_python_files=$($modified_files| grep ".py$\|.ipynb$")
+    - modified_CXX_files=$($modified_files| grep ".h$\|.c$\|.hpp$\|.cpp$\|.cu$")
+    - >
+      if [ ! -z $modified_python_files ]; then
+        python_files_to_format=$(ruff format --check $modified_python_files)
+        echo "PYTHON FILES TO FORMAT : "
+        if [ ! -z "$python_files_to_format" ]; then
+          echo $python_files_to_format
+        else 
+          echo "None"
+        fi
+      fi
+      if [ ! -z $modified_CXX_files ]; then
+        CXX_files_to_format=$(clang-format-12 --dry-run $modified_CXX_files)
+        if [ ! -z "$CXX_files_to_format" ]; then
+          echo $CXX_files_to_format
+        else 
+          echo "None"
+        fi
+      fi
+      if [ ! -z "$python_files_to_format$CXX_files_to_format" ]; then
+        echo "You pushed unformatted files, setup a code formatter before pushing your code."
+        echo "For more informations about code formatting head to the dedicated wiki page :"
+        echo "https://gitlab.eclipse.org/groups/eclipse/aidge/-/wikis/code-quality-:-formatting-&-linting"
+        exit
+      else 
+        echo "No files to format, congratulation!"
+      fi
+