Sort inferred fields

[trueleo]

Description

Fix cases where inferred schema breaks arrow file writer invariants.

Similarly to collect_keys, all fields will be sorted by their name.

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This PR has:

• been tested to ensure log ingestion and log query works.
• added comments explaining the "why" and the intent of the code wherever would not be obvious for an unfamiliar reader.
• added documentation for new or modified features or behaviors.