feat(Collector): add iterators and getters

[Syjalo]

Please describe the changes this PR makes and why it should be merged:
This PR adds new iterators and getters that allow you use collectors without deep nesting.

Status and versioning classification:

• Code changes have been tested against the Discord API, or there are no code changes
• I know how to update typings and have done so, or typings don't need updating
• This PR changes the library's interface (methods or parameters added)
• This PR includes breaking changes (methods removed or renamed, parameters moved or removed)

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[SpaceEEC]

The next_ and the new async iterators look quite similar, these could probably be abstracted, if it doesn't hurt readability too much 👀

[almeidx]

This needs a rebase

[kyranet]

I feel like we shouldn't have async getters. What about waitForCollect()? Same for the other methods.

I also think that it'd be useful to accept an AbortSignal so we can cancel and unregister the listeners earlier.

[kyranet]

This isn't removing the ignore listener that's registering in line 394.

[kyranet]

Also, regarding this description:

This PR adds new iterators and getters that allow you use collectors without deep nesting.

Technically you can achieve the helper iterators by filtering the main iterator:

for await (const [type, value] of collector) {
	if (type !== ...) continue;
}

However, they would use more resources than the dedicated ones, as it registers 2 more events. And the next one can achieved with similar code.

Praying to get async iterator helpers soon so we can do this 🙏🏼:

const next = await collector.filter(([type]) => type === ...).next();