vim: Fix `insert before` in visual modes (#25603)

Closes #22536

Changes:
- Visual and visual block: Cursor at start of selection.
- Visual line: Cursor at start on line.
- Uses different handling since the selection does not actually change
in vline.

Release Notes:

- vim: Fixed insert before (`shift-i`) in visual modes.
ff0bb1f389brian tan committed on 3/5/2025, 4:58:01 AM· committed by GitHubparent9c7eee2
2 files changedLine totals unavailable