Collection Watch - Change Streams

Hi all,

How can I watch Change Streams with monk?
```js
const MongoClient = require("mongodb").MongoClient;
const assert = require("assert");
/*
Modify Change Stream Output using Aggregation Pipelines
You can control change stream output by providing an array of one or more of the following pipeline stages when configuring the change stream:
$match, $project, $addFields, $replaceRoot, $redact
See Change Events for more information on the change stream response document format.
*/
const pipeline = [
{
$project: { documentKey: false }
}
];
MongoClient.connect("mongodb://localhost:27017,localhost:27018,localhost:27019?replicaSet=mongo-repl")
.then(client => {
console.log("Connected correctly to server");
// specify db and collections
const db = client.db("superheroesdb");
const collection = db.collection("superheroes");

const changeStream = collection.watch(pipeline);
// start listen to changes
changeStream.on("change", function(change) {
console.log(change);
});

})
.catch(err => {
console.error(err);
});
```

The issue names no Monk file, test, or entry point. Start by checking how Monk exposes collection operations and whether MongoDB collection.watch is supported; done should be a confirmed, documented way to use change streams or a clearly scoped implementation plan.

Written by the indexing model from the issue text.