feat: Add pmod (positive modulo) scalar function

[natashasehgal]

Summary: Add pmod (positive modulo) as a native Presto scalar function, registered across all numeric types: TINYINT, SMALLINT, INTEGER, BIGINT, DOUBLE, and REAL.

Motivation
pmod is already implemented in the Velox native engine but has no corresponding function registration in the Java coordinator. Without these stubs, the coordinator cannot resolve pmod in query plans, so queries using
it fail during analysis.

Design

• Stubs only: All 6 overloads throw UnsupportedOperationException — actual execution is handled by Velox's PModIntFunction / PModFloatFunction
• Signatures: Strictly (T, T) → T for each type (no cross-type overloads)
• Semantics: Returns the positive remainder of a % n. Returns NULL when n = 0.

Test Plan

• Velox-side tests already exist in ArithmeticTest.cpp covering edge cases (division by zero, MIN_VALUE, negative inputs)
• Java stubs are pass-through — no coordinator-side logic to test

== RELEASE NOTES ==

General Changes

• Add pmod (positive modulo) scalar function for all numeric types (TINYINT, SMALLINT, INTEGER, BIGINT, DOUBLE, REAL). Execution is handled by the native engine; the Java coordinator registers stub declarations for
  query planning.

Differential Revision: D99449450

Summary by Sourcery

New Features:

• Introduce the pmod scalar function that returns the positive remainder for numeric types including tinyint, smallint, integer, bigint, double, and real.

[sourcery-ai]

Reviewer's Guide

Adds a new scalar SQL function pmod to Presto’s MathFunctions with multiple type overloads, declared in Java but delegated entirely to the native engine implementation.

Sequence diagram for query execution using pmod delegated to native engine

sequenceDiagram
    actor User
    participant PrestoClient
    participant PrestoCoordinator
    participant FunctionRegistry
    participant NativeEngine

    User->>PrestoClient: Submit SQL query
    PrestoClient->>PrestoCoordinator: Send query text
    PrestoCoordinator->>FunctionRegistry: Resolve function pmod
    FunctionRegistry-->>PrestoCoordinator: Return MathFunctions.pmod* overload metadata
    PrestoCoordinator->>NativeEngine: Plan and execute pmod with resolved types
    NativeEngine-->>PrestoCoordinator: Return pmod results
    PrestoCoordinator-->>PrestoClient: Return query results
    PrestoClient-->>User: Display results

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Class diagram for new pmod scalar overloads in MathFunctions

classDiagram
    class MathFunctions {
        <<utility>>
        +long pmodTinyint(long num1, long num2)
        +long pmodSmallint(long num1, long num2)
        +long pmodInteger(long num1, long num2)
        +long pmodBigint(long num1, long num2)
        +double pmodDouble(double num1, double num2)
        +long pmodFloat(long num1, long num2)
    }

    class ScalarFunctionAnnotation {
    }

    class DescriptionAnnotation {
    }

    MathFunctions .. ScalarFunctionAnnotation : uses
    MathFunctions .. DescriptionAnnotation : uses

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File-Level Changes

Change	Details	Files
Declare pmod scalar function overloads for integral and floating-point types, delegating execution to the native engine.	Introduce @ScalarFunction("pmod") methods for TINYINT, SMALLINT, INTEGER, BIGINT, DOUBLE, and REAL in MathFunctions Annotate each overload with @Description("positive remainder of given quotient") and appropriate @SqlType signatures Have each method throw UnsupportedOperationException with a message indicating pmod is implemented in the native engine	presto-main-base/src/main/java/com/facebook/presto/operator/scalar/MathFunctions.java

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[sourcery-ai]

Hey - I've left some high level feedback:

• Since these Java stubs are registered as scalar functions but always throw, consider either providing a simple Java implementation or gating registration so non-native engine paths don’t unexpectedly hit UnsupportedOperationException at runtime.
• If this pattern of delegating to the native engine is intentional, align the error message and annotations with other native-only scalar functions in MathFunctions (or a shared helper) for consistency and easier debugging.

Prompt for AI Agents

Please address the comments from this code review:

## Overall Comments
- Since these Java stubs are registered as scalar functions but always throw, consider either providing a simple Java implementation or gating registration so non-native engine paths don’t unexpectedly hit `UnsupportedOperationException` at runtime.
- If this pattern of delegating to the native engine is intentional, align the error message and annotations with other native-only scalar functions in `MathFunctions` (or a shared helper) for consistency and easier debugging.

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