feat: explicitEmptyCollections V2, for more json (or less)

[ThijsBroersen]

A retry of the explicitEmptyCollections feature. The defaults should be exactly as the current release (decoding missing collections will fail).

To tap in on the feature use annotation @jsonExplicitEmptyCollections(false) on fields or case classes or use the JsonCodecConfiguration.explicitEmptyCollections = false config.
After this, all collections and case classes which have empty values will be omitted from the json output and decoding will fill in the missing values with empty collections.

To implement this while keeping performance I introduced three new decoder traits (scope private[json]), to allow to build an efficient decoder. (CollectionJsonDecoder, OptionJsonDecoder, MappedJsonDecoder).

[987Nabil]

@ThijsBroersen I wrote this before in one of the related issues, but I guess you missed it.
Please make it possible to configure the de-/encoding separately. Users might want to explicitly serialize [], but be graceful when receiving messages with the collection field missing.

[ThijsBroersen]

@ThijsBroersen I wrote this before in one of the related issues, but I guess you missed it. Please make it possible to configure the de-/encoding separately. Users might want to explicitly serialize [], but be graceful when receiving messages with the collection field missing.

@987Nabil if you refer to #1235 (comment) that is not how I read it. The goals was to have to feature 100% opt-in. Unlike explicitNulls, the explicitEmptyCollections will apply strict encoding and decoding when the feature is used. So by default everything is as before.

If you say you want to have it configurable separately, how would that config look like? That would need a redesign, adjustment of logic, adjustment of tests.
Would case class jsonExplicitEmptyCollections(enabled: Boolean = true) transform into case class jsonExplicitEmptyCollections(whenDecoding: Boolean = true, whenEncoding: Boolean = true) or another annotation?
What about the JsonCodecConfiguration, use two field? explicitEmptyCollectionsForDecoding: Boolean = true, explicitEmptyCollectionsForEncoding: Boolean = true or explicitEmptyCollections: ExplicitEmptyCollectionsConfig?

[987Nabil]

@ThijsBroersen I do not care that much about the details of the implementation. It is just that these are two different things and she be handled as such im the config. Try it out, see what fits

[ThijsBroersen]

@987Nabil done

[987Nabil]

@ThijsBroersen maybe shorter names for the booleans? They might show up in user land since it is booleans. Maybe just remove the when? Or just encode and decode?