BotBuilder Storage MongoDB

MongoDB storage provider for the Bot Framework JavaScript SDK v4. This library implements the `Storage` interface, allowing bots to persist conversation state, user state, and bot state in a MongoDB database. The current version (1.0.17) supports Node.js 13+ and is compatible with the BotBuilder v4 SDK. It exposes a simple API: create a `MongoDbStorage` instance with a MongoDB collection, then use it with `ConversationState` or `UserState`. The library provides a convenience method `getCollection()` that defaults to database `BotFramework` and collection `BotFrameworkState`, but supports custom names. Compared to the official botbuilder-azure storage, this package is community-maintained and offers a lightweight, pure-MongoDB solution without Azure dependencies.