Allow for asynchronous resolving for DI

[brandonseydel]

🙋 Feature Request

Would like to resolve DI async

🤔 Expected Behavior

Resolves to the correct instance

😯 Current Behavior

Have to await it myself

Repro link https://stackblitz.com/edit/au2-conventions?file=src%2Fmy-app.html

💁 Possible Solution

Await it internally always

🔦 Context

This will help people easily chunk their code

💻 Examples

 Registration.cachedCallback(IEncryptionClient, async () => {
      const LitJsSdk = (await import('lit-js-sdk')).default;
      const client: Partial<IEncryptionClient> = new LitJsSdk.LitNodeClient();
      client.getAuthSig = LitJsSdk.signAndSaveAuthMessage;
      client.encryptString = LitJsSdk.encryptString;
      client.decryptString = LitJsSdk.decryptString;
      client.uint8arrayToString = LitJsSdk.uint8arrayToString;
      return client as IEncryptionClient;
    }),

 private async connect(): Promise<void> {
    if (this.client) return;
//  i have to current await below but would like it to just resolve so I don't have to union type it
    const client = await this.container.get(IEncryptionClient);
    this.client = client;
    return await this.client.connect();
  }