Improve Parallel Reading (CSV, JSON) / Help Wanted

### Is your feature request related to a problem or challenge?

As originally stated in #6922 (I'm not sure why the issue was closed) and discussed in #6801 the current `FileOpener` implementation for both, Csv and Json, are utilizing multiple GetRequests to adjust the byte range prior to parsing / reading the file itself.

This is suboptimal and can be improved - minimizing the latency due to multiple remote network requests.

### Describe the solution you'd like

I would like to reduce the number of GetRequests from 3 to 1.

This can be done by "overfetching" the original partition byte range; and then adjust the range by finding the newline delimiter similar to the solution already implemented.

The approach is outlined here: https://github.com/apache/arrow-datafusion/pull/6801#discussion_r1257465786 by @alamb

There are some edge-cases that need consideration, like "heterogenous object sizes" within a CSV row or JSON object, that leads to partition ranges overlapping on the same line, which can lead to reading the same line twice. Error handling/ retry when no newline can be found ("overfetching" range was to small) has to be handled, as well.

**POC**:
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I already went ahead and implemented a POC which works and can handle some edge-cases like overlapping partition ranges; appropriate error handling / retry is still missing.

However, I definitely **need help** to improve upon this: https://github.com/marvinlanhenke/arrow-datafusion/blob/poc_optimize_get_req/datafusion/core/src/datasource/physical_plan/json.rs#L232-L381

The solution is inefficient due to line-by-line operations and buffer cloning / copying.
I tried different ways to handle the `GetResultPayload::Stream` by using BytesMut::new() & buffer.extend_from_slice; but I was not able to handle all the edge-cases correctly.

I'd greatly appreciate if someone can give some pointers; or take it from here to improve upon the POC.

### Describe alternatives you've considered

Leave as is.

### Additional context

None.

Inizia da datafusion/core/src/datasource/physical_plan/json.rs, in particolare dalla sezione del POC collegata nell’issue, quindi leggi l’approccio discusso in pull request #6801. Traccia la gestione di FileOpener e GetResultPayload::Stream e confronta i percorsi CSV e JSON. Il lavoro è completo quando le letture di intervalli vengono ridotte da tre GetRequests a una, gestendo intervalli sovrapposti, newline mancanti e tentativi ripetuti, ed evitando la copia inefficiente del POC.

Scritto dal modello di indicizzazione a partire dal testo della issue.