Add Event and minimal EventTarget

[MasatoDev]

Overview

Thank you for your confirmation.
I implemented Event and EventTarget that are related to #9 without detailed dispatching logic.

Description

This PR is regarded to bellow spec.

https://dom.spec.whatwg.org/#event
https://dom.spec.whatwg.org/#eventtarget

I referred to the following code.

https://github.com/denoland/deno/blob/main/ext/web/02_event.js

Scope

• Event class
• EventTarget class

out-of-scop items

• dispatching-events
• Case of eventTarget is a Window object or the type is touchstart, touchmove, and so on.

Outstanding issue

• Currently, I need import, but I think Event and EventTarget is Global Scope, so which file should I add and implement?

• Implementation for window and DOM element events is omitted. Please let me know if there is a problem.

• I think there is a discussion about whether to include primordials, but I didn't mention it.

  • refactor: introduce primordials denoland/deno#10939

Test

[syrusakbary]

Waiting on feedback from @Arshia001 on this one

[Arshia001]

Hey @MasatoDev, thank you for your contribution!

Currently, it is impossible to define global objects in JS/TS. However, I think it would be beneficial to add that in, so I'll create an issue for it and move this to the global scope once that's implemented.