Add StrictEventTarget

[Richienb]

Fixes #1230

[fregante]

What does the type do exactly? There are no errors here:

https://www.typescriptlang.org/play/?#code/JYWwDg9gTgLgBDAnmApnAyjKwDGMCiAbigHYwAqAhlAOYrwBmUEIcA5AM5a4wC0KxMrxjU6MNgG4AUFJwQSXBKPpwAvHBIoA7nAAURUhWXxKHBMhQQGGbngNkqtegB4A3lICQDCBABccLmwSGgk4AHowuHt4LWAYAAs4ABNKESkAXwAaOABtTzYAI2o2bIiowRi4+IgAV3gUtIBdAD4ASmkZEScYADok4A4wVJx46N1NHQBhGq4WMbZvCDZW9qkusT6BoZgRsYm4admQecWSuFck+kpgABt-NnJ4lDZ0lel1+k3B4dGK8e0DjMYHM-mwSBBUGcLldbvdHs9XqsPr1+t8dr9DP8pkCQZiFj4oZcRLDzgAPfwAInBJgC3GCAH4KelER1kV9trs-vt5kUoMskcZ2T89gD5tTkigGMBNEk4AU6rTbjc4JQbjcIFoUEl6fyJEA

import type StrictEventTarget from 'strict-event-target';

const target = new (EventTarget as typeof StrictEventTarget<{
	foo: string; // Event with data
}, [
	'bar', // Event without data
]>);


target.dispatchEvent(new CustomEvent('foo'));
target.dispatchEvent(new CustomEvent('foo', {detail: 'The'}));
target.dispatchEvent(new CustomEvent('nope', {detail: 'The'}));
target.dispatchEvent(new CustomEvent('foo', {detail: {x: "not a string?"}}));

target.dispatchEvent(new Event('bar'));
target.dispatchEvent(new Event('not defined but still allowed?'));

[Richienb]

There are no errors here:

Yeah so I wanna fix it here, and deprecate that