Typing a backtick over selected text in Rust, C, and C++ comments
replaced the selection instead of wrapping it. Markdown already supports
this via its backtick bracket pair.

Add a backtick bracket pair for these languages:
  - `surround = true` wraps selections in backticks
  - `close = false` avoids auto-closing lone backticks
  - `not_in = ["string"]` enables it in comments but not strings

Self-Review Checklist:

- [X] I've reviewed my own diff for quality, security, and reliability
- [ ] 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 #58538

Release Notes:

- Added support for surrounding selected text with backticks in Rust, C,
and C++

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Co-authored-by: dino <dinojoaocosta@gmail.com>