[@types/mongoose] Add the paths property to Schema type (#42307)

types/mongoose/index.d.ts

@@ -914,6 +914,13 @@ declare module "mongoose" {
      */
     requiredPaths(invalidate?: boolean): string[];
 
+    /**
+     * Lists all paths and their type in the current schema.
+     */
+    paths: {
+      [key: string]: SchemaType;
+    }
+
     /**
      * Sets/gets a schema option.
      * @param key option name