Allow query parameter for firestore.collection

[dominic-ks]

Hello,

Firstly, thanks for the great NestJS package, really handy.

One thing I've run into is that the FirebaseFirestoreService::collection method doesn't accept the second optional query argument here:

• nestjs-firebase-admin/lib/services/firebase-admin-firestore.service.ts

  Line 19 in 486b693

  collection(collectionPath: string): FirebaseFirestore.CollectionReference {

I can't seem to find the part of the official docs where I first came across this, but as an example @angular/fire allow it here:

• https://github.com/angular/angularfire/blob/3e991a61a8d27047e380593e66bea0089e739153/src/firestore/firestore.ts#L192

It's handy if you want to do things like build dynamic queries by looping through objects.

Is this something that can be added?

Cheers,