In single-line editors like the Find bar, MoveToBeginningOfLine with
stop_at_indent should go directly to column 0 instead of stopping at the
indentation level.

Closes #50634

Before you mark this PR as ready for review, make sure that you have:
- [x] Added a solid test coverage and/or screenshots from doing manual
testing
- [x] Done a self-review taking into account security and performance
aspects
- [ ] Aligned any UI changes with the [UI
checklist](https://github.com/zedindustries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)

Release Notes:

- Fixed `MoveToBeginningOfLine` stopping at indentation in single-line
editors like the Find bar instead of moving to column 0.