[3.13] gh-111201: Improve pyrepl auto indentation (GH-119606) (GH-119833)

- auto-indent when editing multi-line block
- ignore comments

(cherry picked from commit dae0375bd9)

Co-authored-by: Arnon Yaari <wiggin15@yahoo.com>

Lib/test/test_pyrepl/test_reader.py

@@ -168,8 +168,8 @@ def test_newline_within_block_trailing_whitespace(self):
 
         expected = (
             "def foo():\n"
-            "\n"
-            "\n"
+            "    \n"
+            "    \n"
             "    a = 1\n"
             "    \n"
             "    "    # HistoricalReader will trim trailing whitespace