Add JS Loaders

[lucasvallenet]

Create loaders utils based on Fournier.
Reformat app.js with a js class, and add useful methods (load, init, addCustomEvents, setVars) that are triggered on app mount.

The loaders.js and app.js are W.I.P, improvements are welcome !

[mcaskill]

• Regarding the new App class, it's a good convention to have the class and the entry point file be separate:

  A file SHOULD declare new symbols (classes, functions, constants, etc.) and cause no other side effects, or it SHOULD execute logic with side effects, but SHOULD NOT do both.

  The phrase "side effects" means execution of logic not directly related to declaring classes, functions, constants, etc., merely from including the file.
  — PSR-1: Basic Coding Standard, PHP-FIG

• Following the previous, should window.addEventListener('load', () => this.load()) be defined in the entry point file, after creating the App object?

  const app = new App()
  window.addEventListener('load', () => app.load())

• Previously, modular was our "Application". Now that a dedicated App class has been introduced, I suggest renaming the property to this.modular, this.manager, or this.moduleManager.

  Or maybe have App extend the modular class?

• Inline comments (such as "Add custom events", "Set vars", "Window events", "Instanciate app") are somewhat redundant given most of the following lines are self explanatory. If anything, these inline comments should be moved to block comments next to their matching declarations.

[arnvvd]

Outcome from meeting on 2022-10-05
Status: On hold until refactoring.

• We agree with the purpose, but we need some code refactoring. We are waiting for the other merges.