Devcontainer backend dev (#608)

add backend-dev devcontainer and extract openapi.json to docs/

.devcontainer/backend-dev/post_create_command.sh

@@ -0,0 +1,23 @@
+# ensure pre-commit is installed
+pre-commit install
+
+# create python virtual environment
+python3 -m venv .venv
+
+# install python dependencies in /backend
+cd backend
+pip install -r requirements.txt
+cd ..
+
+# install code in editable mode in /oasst-shared
+cd oasst-shared
+pip install -e .
+cd ..
+
+# docker compose up for backend-dev
+docker compose up backend-dev --build --attach-dependencies -d
+
+# note: commented out for now, you probably want to manually run this part once in the devcontainer
+# run run-local.sh script
+# cd scripts/backend-development/
+# bash run-local.sh