feat: log details to message log

[tsundvoll]

to be used for example from the fmu-sumo-uplader
to include a summary of the upload with the logs

Issue

#fmu-sumo-uploader/issues/219

Description

Necessary change to make use of details provided when logging.

How to test

From a library using the LogHandlerSumo, such as fmu-sumo-uploader, make a logging, such as

details = {
    "caseuuid": "1234-5678",
    "ensamblename": "my_ensamble",
    "numbers_of_objects_uploaded": "42",
    "start_time": "2026-06-04T12:00:00Z",
    "end_time": "2026-06-04T12:30:00Z",
}

logger.info("Upload finished",  extra={"details": details})

And observe that data is stored in the message log.

Checklist

• No redundant `print()` statements, commented-out code, or other remnants from the development 👀
• New/refactored code is following same conventions as the rest of the code base 🧬
• New/refactored code is tested ⚙
• Documentation has been updated 🧾
• Commits are semantic ✅

[rwiker]

LGTM.