✨(project) Django boilerplate

This commit introduces a boilerplate inspired by https://github.com/numerique-gouv/impress.
The code has been cleaned to remove unnecessary Impress logic and dependencies.

Changes made:
- Removed Minio, WebRTC, and create bucket from the stack.
- Removed the Next.js frontend (it will be replaced by Vite).
- Cleaned up impress-specific backend logics.

The whole stack remains functional:
- All tests pass.
- Linter checks pass.
- Agent Connexion sources are already set-up.

Why clear out the code?

To adhere to the KISS principle, we aim to maintain a minimalist codebase. Cloning Impress
allowed us to quickly inherit its code quality tools and deployment configurations for staging,
pre-production, and production environments.

What’s broken?
- The tsclient is not functional anymore.
- Some make commands need to be fixed.
- Helm sources are outdated.
- Naming across the project sources are inconsistent (impress, visio, etc.)
- CI is not configured properly.

This list might be incomplete. Let's grind it.

src/mail/package.json

@@ -0,0 +1,22 @@
+{
+  "name": "mail_mjml",
+  "version": "0.1.0",
+  "description": "An util to generate html and text django's templates from mjml templates",
+  "type": "module",
+  "dependencies": {
+    "@html-to/text-cli": "0.5.4",
+    "mjml": "4.15.3"
+  },
+  "private": true,
+  "scripts": {
+    "build-mjml-to-html": "bash ./bin/mjml-to-html",
+    "build-html-to-plain-text": "bash ./bin/html-to-plain-text",
+    "build": "yarn build-mjml-to-html && yarn build-html-to-plain-text"
+  },
+  "volta": {
+    "node": "16.15.1"
+  },
+  "repository": "https://github.com/numerique-gouv/impress",
+  "author": "DINUM",
+  "license": "MIT"
+}