Add support for list type in get (#20332)

Closes: #20326 

There are instances where we result in `list` type in `StringMethods`, for which pandas returns `object` dtype. But calling `.str.xyz` on that result is technically allowed and valid for some APIs. This is pr enables `list` type for `.str.get` API.

Authors:
  - GALI PREM SAGAR (https://github.com/galipremsagar)

Approvers:
  - Matthew Roeschke (https://github.com/mroeschke)

URL: #20332

Author: galipremsagar

python/cudf/cudf/core/accessors/string.py

@@ -16,6 +16,7 @@
 from cudf.api.extensions import no_default
 from cudf.api.types import is_integer, is_scalar
 from cudf.core.accessors.base_accessor import BaseAccessor
+from cudf.core.accessors.lists import ListMethods
 from cudf.core.column.column import ColumnBase, as_column, column_empty
 from cudf.core.dtypes import ListDtype
 from cudf.options import get_option
@@ -2313,6 +2314,8 @@ def get(self, i: int = 0) -> Series | Index:
         2    f
         dtype: object
         """
+        if isinstance(self._column.dtype, ListDtype):
+            return ListMethods(self._parent).get(i)
         str_lens = self.len()
         if i < 0:
             next_index = i - 1

python/cudf/cudf/tests/series/accessors/test_str.py

@@ -2844,3 +2844,18 @@ def test_string_misc_name(ps_gs, name):
     assert_eq(ps + ps, gs + gs)
     assert_eq(ps + "RAPIDS", gs + "RAPIDS")
     assert_eq("RAPIDS" + ps, "RAPIDS" + gs)
+
+
+def test_string_list_get_access():
+    ps = pd.Series(["a,b,c", "d,e,f", None, "g,h,i"])
+    gs = cudf.from_pandas(ps)
+
+    expect = ps.str.split(",")
+    got = gs.str.split(",")
+
+    assert_eq(expect, got)
+
+    expect = expect.str.get(1)
+    got = got.str.get(1)
+
+    assert_eq(expect, got)