Adds support for named bookmarks while preserving the existing unnamed
bookmark workflow.

Main changes:
- Keeps `ToggleBookmark` as the quick unnamed bookmark action.
- Adds `ToggleNamedBookmark`, which prompts for a bookmark name when
adding a new bookmark and removes an existing bookmark on the same line,
including unnamed ones.
- Adds `EditBookmark` support for renaming existing bookmarks.
- Persists bookmark names in workspace storage.
- Adds a project bookmarks picker that supports filtering by bookmark
name and relative path, with highlighted matches.
- Updates bookmark storage and tests to carry bookmark names through
serialization, restoration, navigation, and project-level listing.

Self-Review Checklist:

- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content is consistent with the [UI/UX
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
- [x] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable

Closes #ISSUE

Video
toggle:


https://github.com/user-attachments/assets/a725b9cf-ac37-4ebc-85cc-ee820452c043

rename:


https://github.com/user-attachments/assets/a6d0d0c1-511b-4fb7-ae5d-22c55d1a075f


Release Notes:

- Add named bookmark support

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Co-authored-by: Yara 🏳️‍⚧️ <git@yara.blue>