[BUG] Fix if_else series naming from predicate broadcast (#2051)

When predicate is broadcasted in the if_else kernel and the predicate is
false, the if_false series is cloned and the name is unchanged, which
causes a
```
ValueError: DaftError::ComputeError Mismatch of expected expression name and name from computed series
```
at expression evaluation time because the expected field name is the
[if_true series name.
](https://github.com/Eventual-Inc/Daft/blob/main/src/daft-dsl/src/expr.rs#L530)

Example code to reproduce:
```
df = daft.from_pydict({"predicate": [False], "if_true": ["true"], "if_false": ["false"]})
df = df.select((df["predicate"] == True).if_else(df["if_true"], df["if_false"]))
df.show()
```

src/daft-core/src/array/ops/if_else.rs

@@ -23,9 +23,9 @@ fn generic_if_else<T: GrowableArray + FullNull + Clone + IntoSeries>(
             None => Ok(T::full_null(name, dtype, lhs_len).into_series()),
             Some(predicate_scalar_value) => {
                 if predicate_scalar_value {
-                    Ok(lhs.clone().into_series())
+                    Ok(lhs.clone().into_series().rename(name))
                 } else {
-                    Ok(rhs.clone().into_series())
+                    Ok(rhs.clone().into_series().rename(name))
                 }
             }
         };

tests/table/test_if_else.py

@@ -0,0 +1,25 @@
+from __future__ import annotations
+
+import pytest
+
+from daft.expressions import col
+from daft.table.micropartition import MicroPartition
+
+
+@pytest.mark.parametrize(
+    ["predicate", "if_true", "if_false", "expected"],
+    [
+        # Single row
+        ([True], [1], [2], [1]),
+        ([False], [1], [2], [2]),
+        # Multiple rows
+        ([True, False, True], [1, 2, 3], [4, 5, 6], [1, 5, 3]),
+        ([False, False, False], [1, 2, 3], [4, 5, 6], [4, 5, 6]),
+    ],
+)
+def test_table_expr_if_else(predicate, if_true, if_false, expected) -> None:
+    daft_table = MicroPartition.from_pydict({"predicate": predicate, "if_true": if_true, "if_false": if_false})
+    daft_table = daft_table.eval_expression_list([col("predicate").if_else(col("if_true"), col("if_false"))])
+    pydict = daft_table.to_pydict()
+
+    assert pydict["if_true"] == expected