Feature request: Add support for projection operators

[CarlosLozanoHealthCaters]

Hey! MongoDB allows doing projections with operators in find queries (https://www.mongodb.com/docs/v6.0/reference/operator/projection/)

Example
Considering the following schema:

const userSchema = schema({
    firstName: types.string({ required: true }),
    lastName: types.string({ required: true }),
    grades: types.array(types.number())
});
const User = papr.model('users', userSchema);

And having the following info stored:

{
  firstName: 'John',
  lastName: 'Smith',
  grades: [9, 8, 10]
}

The following query:

const userInfo = await User.find({
    firstName: 'John'
}, {
    projection: {
        firstName: 1,
        grades: {$slice: 1}
    }
});

should output the following data:

{
  firstName: 'John',
  grades: [9]
}

Current issue
The current version force you to set a number in the projection field and doesn't allow you to include projection operators.

Probably we only need to change the following types:

• export declare type ProjectionType<TSchema extends BaseSchema, Projection extends Partial<Record<Join<NestedPaths<WithId<TSchema>>, '.'>, number>> | undefined> = undefined extends Projection ? WithId<TSchema> : WithId<DeepPick<TSchema, '_id' | (keyof Projection & string)>>;
• export declare type Projection<TSchema> = Partial<Record<Join<NestedPaths<WithId<TSchema>>, '.'>, number>>;

These types have a Record with values as numbers. I believe that it would be enough changing those Records, but I would like to get the community knowledge here.

Thanks!