Native map construction doesn't match Spark 4.0+ float key normalization (-0.0 keys, missing DUPLICATED_MAP_KEY) #6549

Describe the bug

Since Spark 4.0, ArrayBasedMapBuilder normalizes floating-point map keys before it checks for duplicates. -0.0 becomes 0.0 and NaN is canonicalized, unless spark.sql.legacy.disableMapKeyNormalization is set. Spark 3.4 and 3.5 don't normalize map keys.

Comet's native map construction doesn't fully match this. With the Spark 4.1 profile and default configs on branch-1.1:

• map_from_entries keeps a -0.0 key, where Spark returns 0.0.
• map_from_entries and map_from_arrays both accept 0.0 and -0.0 as two keys in the same map, where Spark raises DUPLICATED_MAP_KEY.
• map_from_arrays does normalize a lone -0.0 key, so only its duplicate check differs.

The wrong keys flow into anything downstream, for example explode(map_keys(...)). CometMapFromArrays and CometMapFromEntries report Compatible for float and double keys, so this runs natively by default. Map lookups on float keys already fall back for this reason (#5580), but map construction doesn't.

Steps to reproduce

-- Spark 4.0, 4.1 or 4.2, default configs
CREATE TABLE fmk_neg(k ARRAY<DOUBLE>, v ARRAY<INT>) USING parquet;
INSERT INTO fmk_neg VALUES (array(CAST('-0.0' AS DOUBLE), 1.5D), array(10, 20));

SELECT map_from_entries(arrays_zip(k, v)) FROM fmk_neg;
-- Spark: {0.0 -> 10, 1.5 -> 20}
-- Comet: {-0.0 -> 10, 1.5 -> 20}

SELECT key FROM fmk_neg LATERAL VIEW explode(map_keys(map_from_entries(arrays_zip(k, v)))) e AS key;
-- Spark: 0.0, 1.5
-- Comet: -0.0, 1.5

CREATE TABLE fmk_dup(k ARRAY<DOUBLE>, v ARRAY<INT>) USING parquet;
INSERT INTO fmk_dup VALUES (array(0.0D, CAST('-0.0' AS DOUBLE)), array(1, 2));

SELECT map_from_entries(arrays_zip(k, v)) FROM fmk_dup;
SELECT map_from_arrays(k, v) FROM fmk_dup;
-- Spark: DUPLICATED_MAP_KEY for both
-- Comet: both return a map

I ran these as SQL file tests on branch-1.1 at 1de7e7d with the default Spark 4.1.3 profile. SELECT map_from_arrays(k, v) FROM fmk_neg, and map_concat over it, matched Spark.

Expected behavior

On Spark 4.0+, match Spark: normalize float and double keys before the duplicate check, honoring spark.sql.legacy.disableMapKeyNormalization. Until the native kernels do that, fall back to Spark for float and double keys on Spark 4.0+.

Additional context

• I found this while reviewing feat: support map inputs for explode #6107, which makes map explode native and so adds one more consumer of these keys. The bug predates that PR.
• create_map with float keys hasn't been checked.
• Related to [EPIC] Match Spark's -0.0 and NaN semantics systematically instead of per expression #6385.