gh-4873: configurable Document.toJson() serialization for logging

[rfelgent]

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[rfelgent]

Hi @mp911de ,

after looking into the code, I would like to discuss options with you.

1. introduce XXXDelegate class for logging serialization (with refactoring of MongoTemplate/ReactiveMongoTemplate)
2. add SerializationUtils#serializeToJsonSafely(@Nullable Document document, JsonWriterSettings settings) {} (with refactoring of MongoTemplate/ReactiveMongoTemplate)
3. introduce a Log-EntityCallback to log Document before persisting it to data base (no refactoring of MongoTemplate/ReactiveMongoTemplate). This will not work for "query()" logs, will it ? Is it a valid requirement ?
4. shouldn't the mongodb-driver itself provide this logging functionality (json and bson) ?

If we want to put hands on it, my preference is option 3) otherwise option 4). What dou you think ?

Furthermore, is there another way to discuss ideas and implementation details with you apart form comments in pull requests ?