add skaffold

[lucido-simon]

This PR adds Skaffold as a dev solution. The main idea is to replicate a close to production environment while developing applications.

The goal was to push a developer experience that doesn't compromise ease of use like you would on a local development environment using docker compose and nodemon. When running skaffold dev, skaffold will build docker images, push them to the cluster in the current kubernetes context, and sync any source code modifications by copying file directly inside the container. This means that, excepts on first launch, no other docker build happens. This allows for extremely fast iterations, just like you would on a more traditional setup.

To do so, this PR brings the following changes:

• Retry DB connections, inside the database module. This is to avoid api crashes on first startup, when the database is not yet ready.
• A dev dockerfile, that launches the app in development mode, watching for source file changes.
• Kustomize templates for the api and www apps, with local overlays that takes into account specificities of a dev environment. For example, we start a postgres with the API, so that the developer doesn't have to start one when developing.
• Skaffold configuration

Any feedback is welcome