vim: Make each vim repeat its own transaction (#41735)

Release Notes:

- Pressing `u` after multiple `.` in rapid succession will now only undo
the latest repeat instead of all repeats.

---------

Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>

crates/vim/test_data/test_repeat_grouping_41735.json

@@ -0,0 +1,10 @@
+{"Put":{"state":"ˇ"}}
+{"Key":"i"}
+{"Key":"a"}
+{"Key":"escape"}
+{"Key":"."}
+{"Key":"."}
+{"Key":"."}
+{"Get":{"state":"ˇaaaa","mode":"Normal"}}
+{"Key":"u"}
+{"Get":{"state":"ˇaaa","mode":"Normal"}}