Build the repository on a reliable framework for local & production

[MathieuLamiot]

Context
The current repository is built with wp-env. Some doubts were emitted regarding the suitability of this for production, and some troubles were encountered for local testing as well.
@nicomollet did some mitigations/work-around and added new commands. Maybe this is enough to make the repository suited for production, maybe not? Also, the possibility to investigated Bedrock was mentionned.

Expected behavior
A suitable architecture and framework for the repository must be selected and implemented.
The framework must allow:

• local testing easily
• to manage dependencies easily (to update external plugins, WP version, etc.). If possible, it should be easier than with wp-rocket.me for instance.

Acceptance Criteria
Local testing must be easy and checked by several teammates on different configurations.
A clear plan for production deployment must be validated.