Refactor Spark bitshift signature (apache#18649)

## Which issue does this PR close?

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Part of apache#12725

## Rationale for this change

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Prefer to avoid user_defined for consistency in function definitions.

## What changes are included in this PR?

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Refactor signature of Spark bit shift functions (left, right, right
unsigned) to use coercion API instead of being user defined.

Also refactor the bit shift code to have a common base struct.

Move the Rust unit tests to SLTs.

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Existing tests.

## Are there any user-facing changes?

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No.

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Author: Jefffrey

datafusion/functions/src/macros.rs

@@ -77,7 +77,8 @@ macro_rules! export_functions {
 }
 
 /// Creates a singleton `ScalarUDF` of the `$UDF` function and a function
-/// named `$NAME` which returns that singleton.
+/// named `$NAME` which returns that singleton. Optionally use a custom constructor
+/// `$CTOR` which defaults to `$UDF::new()` if not specified.
 ///
 /// This is used to ensure creating the list of `ScalarUDF` only happens once.
 #[macro_export]
@@ -97,6 +98,21 @@ macro_rules! make_udf_function {
             std::sync::Arc::clone(&INSTANCE)
         }
     };
+    ($UDF:ty, $NAME:ident, $CTOR:path) => {
+        #[allow(rustdoc::redundant_explicit_links)]
+        #[doc = concat!("Return a [`ScalarUDF`](datafusion_expr::ScalarUDF) implementation of ", stringify!($NAME))]
+        pub fn $NAME() -> std::sync::Arc<datafusion_expr::ScalarUDF> {
+            // Singleton instance of the function
+            static INSTANCE: std::sync::LazyLock<
+                std::sync::Arc<datafusion_expr::ScalarUDF>,
+            > = std::sync::LazyLock::new(|| {
+                std::sync::Arc::new(datafusion_expr::ScalarUDF::new_from_impl(
+                    $CTOR(),
+                ))
+            });
+            std::sync::Arc::clone(&INSTANCE)
+        }
+    };
 }
 
 /// Creates a singleton `ScalarUDF` of the `$UDF` function and a function