Most elegant way I could figure to fix from_json

[PacificBird]

PR Info

Closes #3175

It's honestly not the prettiest fix in the world, but as I mention in the comments of the original issue this is a very difficult problem to solve cleanly. Modified-deserialization-by-proxy is very much not an intended or supported use case of serde. I tried a fully macro-based implementation of from_json, but ran into big problems of the duplication of work between the derives for Models and ActiveModels. In any case I do believe that this is the least-bad way to solve this general design problem short of a very clever workaround and a big refactor, so I'm happy with

I took the idea of making the dummy map by doing a round trip from the dummy active model, to model, into a JSON map using serde_json::to_values, and then merging with serde_json::Map::append with the input JSON values from the AI slop pull, although I hand-coded all of the active model and macro logic without the use of any AI (I straight up don't have a subscription to any and my laptop is not powerful enough to meaningful run a local model...). I did initially copy and then heavily modify the regression test from that PR to test both time and chrono. I left the original comment explaining the test though, I hope that's okay.

The addition of ColumnTrait::serialize_json_key was a necessary evil, as I needed a way to map the serialized keys from roundtripping the dummy values into their deserialize keys so that the final conversion of the merged map into a model (and ultimately an active model) would actually see the dummy values. The way I did it is pretty simple, I just made a HashMap by iterating over Column::iter keyed by the serialize keys from json_key_serialize to the deserialize keys from json_key. That's then used to remap the keys from the dummy values.

This pull may not be my cleanest Rust work, sorry about that. Running rust-analyzer on this codebase eats all of my RAM and soft-locks Linux for me...

Checklist

• I have read the AI Policy and confirm that this contribution complies with it.

Release Notes

• Fix incorrect deserialization of missing DateTime (both time and chrono fields) for ActiveModel::from_json
• Add method: ColumnTrait::serialize_json_key as well as macro implementations for it in DeriveEntityTrait.

Because the new trait method has a default implementation, the addition does not constitute a breaking version change!

[PacificBird]

Added changes for these review comments and also ensured that for #[serde(rename/-all = "...")] (i.e., symmetric ser/de names), it will apply to both serialize and deserialize json keys.

[PacificBird]

not sure if maintainers can rerun tests, the failing test is some sort of CI error, not a failing test