fix: event mixin types

[Zyie]

Ok so this PR was a fun rabbit hole 😄

Overview

The main overview of what this PR is actually changing is that i have removed the abstraction of IFederatedEventTarget in favour of just using Container. IFederatedContainer is still mixed into the Container, which means that all types should work as before.

I believe this change reflects a more accurate description of what object is stored in an FederatedEvent.

The benefits of this is that we don't need to do any typescript magic that decouples the two different implementations of EventEmitter e.g

This

export interface Container<C extends ContainerChild>
    extends Omit<PixiMixins.Container<C>, keyof EventEmitter<ContainerEvents<C> & AnyEvent>>,
    EventEmitter<ContainerEvents<C> & AnyEvent> { }

Becomes this

export interface Container<C extends ContainerChild>
    extends PixiMixins.Container<C>, EventEmitter<ContainerEvents<C> & AnyEvent> {}

What Is This Fixing

The current implementation revealed a nasty bug with using our PixiMixins that is hidden in v7 due to Container extending DisplayObject and everyone will be attaching there custom properties to Container, not DisplayObject, because of this we have never seen the issue.

Hopefully i can try and explain it here...

If you try to add your own properties to Container in v8 currently like this:

declare namespace PixiMixins {
    interface Container {
        overrideMethod(): void
		returnThis(): this
    }
}

Then you try to override and use these methods like:

class NewContainer extends Container {
    testProperty: number;
    override overrideMethod(layout: ComputedLayout) {}
}

const container = new NewContainer();
const container2 = container.returnThis();
container.testProperty // type error: does not exist

We get two TS errors:

• Class 'Container defines instance member property overrideMethod, but extended class NewContainer defines it as instance member function.
• Property 'testProperty' does not exist on type Container

The first issue is that typescript believe the overrideMethod is a property on Container and not a method. So it wants you to declare it like this

override overrideMethod = (layout: ComputedLayout) => {}

However this isn't accurate as if we wanted to declare it as a property it should be defined like this

declare namespace PixiMixins {
    interface Container {
        overrideMethod: ()=> void
    }
}

The second issue is that this is not being respected correctly. It should be returning NewContainer, however it always returns Container

Now I have zero idea what sort of typescript magic is going on that messes up these types so badly but the change here is minimal and seems to work.

[korbit-ai]

My review is in progress 📖 - I will have feedback for you in a few minutes!

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[korbit-ai]

I have reviewed your code and found 6 potential issues. To discuss my individual comments that I have added, tag me in replies using @korbit-ai.

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[bigtimebuddy]

I like this change. Flattening the layers of abstractions for events is welcome.