Helper methods from mongo-scala-driver don't work inside unchecked

[edubrovski]

Steps to reproduce the behavior

Compiling this code

import org.mongodb.scala.model.Filters._

val q = query[TestClass](x => x.intField >= 3 && unchecked(lt("intField", 42)))

fails with

Expected the subquery inside 'unchecked(...)' to have 'org.mongodb.scala.bson.BsonDocument' type, but the subquery is 'org.mongodb.scala.model.Filters.lt[scala.Int]("intField", 42)'

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