Closes https://github.com/zed-industries/zed/issues/19569

Current behavior:


https://github.com/user-attachments/assets/1de764c9-7c62-49ad-b24b-6e85760857db

After PR:


https://github.com/user-attachments/assets/651d8e50-95e2-4513-852b-9557d00d2b62

Release Notes:

- Unified selection directions when performing `editor: select all
selections`.

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Co-authored-by: Marshall Bowers <git@maxdeviant.com>