feat: allow setting train=False and name on indices (#2586)

Enables two new parameters when building indices:

* `name`: Allows explicitly setting a name on the index. Default is
`{col_name}_idx`.
* `train` (default `True`): When set to `False`, an empty index will be
immediately created.

The upgrade of Lance means there are also additional behaviors from
cd76a993b8:

* When a scalar index is created on a Table, it will be kept around even
if all rows are deleted or updated.
* Scalar indices can be created on empty tables. They will default to
`train=False` if the table is empty.

---------

Co-authored-by: Weston Pace <weston.pace@gmail.com>

python/src/table.rs

@@ -341,13 +341,15 @@ impl Table {
         })
     }
 
-    #[pyo3(signature = (column, index=None, replace=None, wait_timeout=None))]
+    #[pyo3(signature = (column, index=None, replace=None, wait_timeout=None, *, name=None, train=None))]
     pub fn create_index<'a>(
         self_: PyRef<'a, Self>,
         column: String,
         index: Option<Bound<'_, PyAny>>,
         replace: Option<bool>,
         wait_timeout: Option<Bound<'_, PyAny>>,
+        name: Option<String>,
+        train: Option<bool>,
     ) -> PyResult<Bound<'a, PyAny>> {
         let index = extract_index_params(&index)?;
         let timeout = wait_timeout.map(|t| t.extract::<std::time::Duration>().unwrap());
@@ -357,6 +359,12 @@ impl Table {
         if let Some(replace) = replace {
             op = op.replace(replace);
         }
+        if let Some(name) = name {
+            op = op.name(name);
+        }
+        if let Some(train) = train {
+            op = op.train(train);
+        }
 
         future_into_py(self_.py(), async move {
             op.execute().await.infer_error()?;