MOD-14559 Fix float serialization precision for typed FPHA arrays

[AvivDavid23]

When serializing typed float arrays, values were promoted to f64 (via INumber) before being passed to serde_json's serialize_f64. This caused serde_json's ryu formatter to produce unnecessarily long decimal strings, because ryu needs more digits to uniquely identify a value among all f64s than among all f32s.

For example, 0.3 stored in an F32 array would serialize as "0.30000001192092896" instead of "0.3".

The fix bypasses the IValue/INumber conversion for F32/F16/BF16 typed arrays during serialization, instead passing the raw float values directly to serde. This routes F32 values through serialize_f32 (and F16/BF16 through serialize_f32 via f32::from()), where ryu's f32 algorithm produces the shortest string that round-trips through f32 — matching user expectations.

Performance:

Version	Mean avg (ms)	Improvement
Before (original, promote to IValue/f64)	62.9	baseline
After (arithmetic round_to_sig_digits)	47.3	1.33x faster than original

---

Note

Medium Risk
Changes JSON serialization output for typed F32/F16/BF16 arrays, which may affect downstream consumers that relied on the previous (over-precise) decimal strings. Logic adds custom rounding/round-trip checks for half types, so edge cases around non-finite values and precision boundaries need review.

Overview
Fixes typed float array JSON serialization to avoid promoting elements through INumber/f64, which previously caused serde_json/ryu to emit overly long decimal strings (e.g. 0.3 becoming 0.30000001192092896).

IArray::serialize now special-cases ArraySliceRef::F32 to serialize elements as f32, and ArraySliceRef::F16/BF16 to compute the shortest decimal that round-trips through the stored half-precision value (via round_to_sig_digits + find_shortest_roundtrip_f64) before serializing. Adds unit tests covering short formatting, round-trip stability across F16/BF16/F32/F64, and expected precision-loss cases (including negatives).

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Cursor Bugbot has reviewed your changes and found 1 potential issue.

There are 2 total unresolved issues (including 1 from previous review).

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[gabsow]

run some preformence test

[gabsow]

run some pr