Export types to be able to extend from the Mongoose class

[nivida]

Prerequisites

• I have written a descriptive issue title
• I have searched existing issues to ensure the bug has not already been reported

Mongoose version

6.6.1

Node.js version

18.x

MongoDB server version

5.x

Description

Currently the type definitions only export mongoose as module but don't allow to import the actual Mongoose class so that we can extend in TS from.

Steps to Reproduce

import {Mongoose} from 'mongoose'

export class Database extends Mongoose {
  ....

  public async connect(): Promise<boolean> {
    ...
    
    await supper.connect(...);
    return true;
  }
}

Expected Behavior

I'm able to extend the base Mongoose class within TypeScript.

[IslandRhythms]

import {Mongoose} from 'mongoose'

export class Database extends Mongoose {

  public async connect(): Promise<boolean> {
    await this.connect();
    return true;
  }
}