fix(index.d.ts): improve autocomplete for new Model() by making doc an object with correct keys

Fix #10475
Re: #10343
Re: #10302

Author: vkarpov15

index.d.ts

@@ -750,12 +750,13 @@ declare module 'mongoose' {
     discriminator<T, U extends Model<T>>(name: string | number, schema: Schema<T, U>, value?: string | number | ObjectId): U;
   }
 
+  type AnyKeys<T> = Partial<{ [P in keyof T]: T[P] | any }>;
   interface AnyObject { [k: string]: any }
   type EnforceDocument<T, TMethods> = T extends Document ? T : T & Document<any, any, T> & TMethods;
 
   export const Model: Model<any>;
   interface Model<T, TQueryHelpers = {}, TMethods = {}> extends NodeJS.EventEmitter, AcceptsDiscriminator {
-    new(doc?: T | any): EnforceDocument<T, TMethods>;
+    new(doc?: AnyKeys<T> & AnyObject): EnforceDocument<T, TMethods>;
 
     aggregate<R = any>(pipeline?: any[]): Aggregate<Array<R>>;
     aggregate<R = any>(pipeline: any[], cb: Function): Promise<Array<R>>;