Fix AI Context menu text wrapping causing overlap (#21438)

Closes https://github.com/zed-industries/zed/issues/20678

| Before | After |
| --- | --- |
| <img width="672" alt="SCR-20241203-jreb"
src="https://github.com/user-attachments/assets/411ba2a6-712f-4ab7-a320-12ac9a35c1e1">
| <img width="771" alt="SCR-20241203-jwhe"
src="https://github.com/user-attachments/assets/022c8ee9-4089-4c09-aa4b-12a0f5528822">
|

Release Notes:

- Fixed AI Context menu text wrapping causing overlap.

Also cc #21409 @WeetHet @osiewicz to use `Label`, this PR has been fixed
`Label` to ensure `whitespace_nowrap` when use `single_line`.

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Co-authored-by: Danilo Leal <daniloleal09@gmail.com>