Move ChannelType typings to within discord.js module

[MitchTalmadge]

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The ChannelType enum typings are declared at the top of typings/index.d.ts, outside of the discord.js module. Thus, they appear at the root of all TypeScript projects which have discord.js in their packages.

Type Definition:

discord.js/typings/index.d.ts

Lines 1 to 10 in b8fd3f6

	declare enum ChannelType {
	text = 0,
	dm = 1,
	voice = 2,
	group = 3,
	category = 4,
	news = 5,
	store = 6,
	unknown = 7,
	}

For example, if I import discord.js as follows:

import * as Discord from "discord.js";

then I would expect to access ChannelType as such:

let myType = Discord.ChannelType.text;

Instead, ChannelType appears at the root:

let myType = ChannelType.text;

and gives an error at runtime:

ReferenceError: ChannelType is not defined

Describe the ideal solution
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Move ChannelType typings into the discord.js module.

Describe alternatives you've considered
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I need to use this for GuildCreateChannelOptions as seen here:

discord.js/typings/index.d.ts

Lines 2562 to 2565 in b8fd3f6

	type?: Exclude<
	keyof typeof ChannelType | ChannelType,
	'dm' | 'group' | 'unknown' | ChannelType.dm | ChannelType.group | ChannelType.unknown
	>;

So for now I just use the any type and assign "text" or "voice" as needed.

Additional context
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I've noticed a near duplicate inside Constants:

discord.js/typings/index.d.ts

Lines 556 to 564 in b8fd3f6

	ChannelTypes: {
	TEXT: 0;
	DM: 1;
	VOICE: 2;
	GROUP: 3;
	CATEGORY: 4;
	NEWS: 5;
	STORE: 6;
	};

Not sure what to do with this.

[SpaceEEC]

As of #5456, you can now access the enum through Discord.Constants.ChannelTypes:

discord.js/typings/index.d.ts

Line 663 in a1f763e

ChannelTypes: typeof ChannelTypes;