feat: add support for using keyword on discord.js Client and WebSocketManager (#10063)

* feat: add support for `using` keyword on client

* fix: use async dispose

* feat: add support for web socket manager disposing

* fix: use interface for client

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Co-authored-by: kodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>

packages/discord.js/typings/index.d.ts

@@ -517,7 +517,7 @@ export abstract class Base {
   public valueOf(): string;
 }
 
-export class BaseClient extends EventEmitter {
+export class BaseClient extends EventEmitter implements AsyncDisposable {
   public constructor(options?: ClientOptions | WebhookClientOptions);
   private decrementMaxListeners(): void;
   private incrementMaxListeners(): void;
@@ -526,6 +526,7 @@ export class BaseClient extends EventEmitter {
   public rest: REST;
   public destroy(): void;
   public toJSON(...props: Record<string, boolean | string>[]): unknown;
+  public [Symbol.asyncDispose](): Promise<void>;
 }
 
 export type GuildCacheMessage<Cached extends CacheType> = CacheTypeReducer<