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 clang-format-12
+    - pip install ruff
+  script: 
+    - set -x
+    - echo "Ensuring that all python files modified in previous commit are correctly formatted. If not, this job will fail."
+    - modified_files=$(git diff --name-only HEAD origin/dev) # change "dev" to $CI_DEFAULT_BRANCH when whole codebase is formatted
+    - nothing_found=true # just an alias to ease reading
+    - modified_python_files=$(echo $modified_files | grep ".py$\|.ipynb$" || true )
+    - modified_CXX_files=$(echo $modified_files | grep ".h$\|.c$\|.hpp$\|.cpp$\|.cu$" || true )
+    - >
+      if [[ -n $modified_python_files ]]; then
+        python_files_to_format=$(ruff format --check $modified_python_files)
+        python_files_to_format=$(( $python_files_to_format != "" ? $python_files_to_format : ""))
+        echo "PYTHON FILES TO FORMAT :"
+        echo "$python_files_to_format"
+      fi
+    - >
+      if [[ -n $modified_CXX_files ]]; then
+        CXX_files_to_format=$(clang-format-12 --dry-run $modified_CXX_files)
+        CXX_files_to_format=$(( $CXX_files_to_format != "" ? $CXX_files_to_format : ""))
+        echo "CXX FILES TO FORMAT :"
+        echo "$CXX_files_to_format"
+      fi
+    - >
+      if [[ "$python_files_to_format$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, congratulations!"
+      fi