Align Iceberg bucket function parameter order with Presto/SQL convention

[Copilot]

Velox's Iceberg bucket function used bucket(numBuckets, input) while Presto PR #25951 and SQL engines (Trino, Presto) use bucket(value, numBuckets). This change swaps the parameter order to match SQL conventions.

Changes

• Function signature: Swapped parameter order in all BucketFunction and BucketDecimalFunction template methods from call(out, numBuckets, input) to call(out, input, numBuckets)
• Registration: Updated registerBucketFunctions() to register types in new order: <ReturnType, InputType, int32_t> instead of <ReturnType, int32_t, InputType>
• Tests: Updated all test cases and helper functions to pass parameters in new order
• Documentation: Updated RST docs with new signature and examples

Example

-- Old signature
SELECT bucket(128, 'abcd');  -- Returns 4

-- New signature (matches Presto/Trino)
SELECT bucket('abcd', 128);  -- Returns 4

Affects all supported types: INTEGER, BIGINT, DECIMAL, DATE, TIMESTAMP, VARCHAR, VARBINARY.

Original prompt

is facebookincubator#13174 and prestodb/presto#25951 same? I need to implement the prestodb/presto#25951 in velox

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