Check query object before $eq in update

[cayasso]

This fails without the first commit fix:

await db.update({ id: '1' }, { $inc: { seq: 1 } })

[cayasso]

Hey, as you can see most of the changes added are small changes, the only important change that can be a breaking change is the BSON upgrade which now exports ObjectId instead of ObjectID.
Thank you for this module!

[RangerMauve]

Are the extra changes with the sub-encoder and updated bson module strictly necessary? I notice there is also an empty watch method that got added.