MongoDB 4.4 compatibility problems

Nobody has claimed this yet.

With MongoDB 4.4 Path Collision Restrictions were introduced (https://docs.mongodb.com/manual/release-notes/4.4-compatibility/#path-collision-restrictions), as a result some queries do not work using this connector anymore.

## Steps to reproduce
We are running a nodejs app over loopback3 that is using this connector to connect to a MongoDB 4.2 atlas cluster.

Package versions:

>
> "loopback": "3.28.0",
> "loopback-connector-mongodb": "5.5.0",

Considering dataModel as an object with:

```
data : {
id: 1,
total: {
day: [1,2,3],
month: [4,5,6],
year: [7,8,9]
}
}
```

The following query will result in a path collision error:
`data = await this.dataModel.findById({ id: this.Id, filter: { fields: ['total', 'total.month'] } });`

And if you update the syntax to follow the MongoDB 4.4 requirements, the query returns an empty object:
`data = await this.dataModel.findById({ id: Id, filter: { fields: ['total.month'] } });`

## Current Behavior

When using the syntax that MongoDB needs in version 4.4 the response comes with no data, and if you try to use the old syntax mongoDB will reject the query with a path collision error.

## Expected Behavior

This query should return data since when it is done directly to MongoDB without using the connector it works
`data = await this.dataModel.findById({ id: this.Id, filter: { fields: ['total.month'] } });`

data should store the object:
`{total.month : [4,5,6]}`

## Additional information

I do not know if this is intended or the connector only supports MongoDB 4.2 or lower versions.

Start by reproducing the findById field-selection queries with loopback-connector-mongodb 5.5.0, LoopBack 3.28.0, and MongoDB 4.2 or 4.4. Inspect how the connector translates nested fields such as total.month, then compare its result with the direct MongoDB query. Done means the nested projection returns the expected data without a path-collision error.

Written by the indexing model from the issue text.