Allow different serializer to an Annotated type for python and json mode

[ChillPC]

Change Summary

PlainSerializer and WrapSerializer can take the arguments :

• when_used as a str like before or a set containing the literals python and/or json
• unless_none as a bool

It will permit to have custom different serializer for the python and json mode using a JsonOrPythonSchema.

Related issue number

fix #8086

Checklist

• The pull request title is a good summary of the changes - it will be used in the changelog
• Unit tests for the changes exist
• Tests pass on CI
• Documentation reflects the changes where applicable
• My PR is ready to review, please add a comment including the phrase "please review" to assign reviewers

[codspeed-hq]

CodSpeed Performance Report

Merging #8432 will not alter performance

_{Comparing ChillPC:different-serializer-mode (ad378db) with main (19fa86c)}

Summary

✅ 10 untouched benchmarks

[ChillPC]

Hello, I am afraid this MR will not be possible without touching the pydantic-core because of the test not passing. The python serializer of the JsonOrPythonSchema is applied whenever model_dump is called (the mode change nothing). The json serializer is used only when model_dump_json is called.

[sydney-runkle]

@ChillPC,

Thanks for your work on this! I'll chat with @davidhewitt on Monday about this, given that he did some advising on the initial issue 👍.

I think we'll probably include this new feature in 2.7.0... but stay tuned :).