BSON format support

[chkp-roeym]

Hi,

It would be great if you could add support for BSON marshal/unmarshal as an additional flag, similar to the existing '-json' or '-sql' flags. When the '-bson' flag is enabled, the generated code should include methods that implement the following APIs from the repository:

"go.mongodb.org/mongo-driver/bson"

required interfaces:

type Marshaler interface {
	MarshalBSON() ([]byte, error)
}

type ValueMarshaler interface {
	MarshalBSONValue() (bsontype.Type, []byte, error)
}

type Unmarshaler interface {
	UnmarshalBSON([]byte) error
}

type ValueUnmarshaler interface {
	UnmarshalBSONValue(bsontype.Type, []byte) error
}

also the following interfaces for using the enum as a key in a map:

"go.mongodb.org/mongo-driver/bson/bsoncodec/map_codec.go"

type KeyMarshaler interface {
	MarshalKey() (key string, err error)
}

type KeyUnmarshaler interface {
	UnmarshalKey(key string) error
}

Thanks!