feat(NODE-7125): expose db and client

Author: durran

src/collection.ts

@@ -192,6 +192,13 @@ export class Collection<TSchema extends Document = Document> {
     this.client = db.client;
   }
 
+  /**
+   * Get the database object for the collection.
+   */
+  get db(): Db {
+    return this.s.db;
+  }
+
   /**
    * The name of the database this collection belongs to
    */

src/db.ts

@@ -126,7 +126,7 @@ export class Db {
   /** @internal */
   s: DbPrivate;
 
-  /** @internal */
+  /** @public */
   readonly client: MongoClient;
 
   public static SYSTEM_NAMESPACE_COLLECTION = CONSTANTS.SYSTEM_NAMESPACE_COLLECTION;