## Objective

Prevent rewrap from breaking at whitespace that Unicode classifies as
non-breaking.

The original approach, prompted by #59664, treated every non-ASCII
whitespace character as unbreakable. Unicode classifies `U+2009 THIN
SPACE` as breakable and `U+202F NARROW NO-BREAK SPACE` as its
non-breaking counterpart.

## Solution

- Treat `U+00A0 NO-BREAK SPACE`, `U+2007 FIGURE SPACE`, and `U+202F
NARROW NO-BREAK SPACE` as part of the surrounding word
- Keep thin spaces, em spaces, and other Unicode breaking spaces as
line-break opportunities
- Cover all three non-breaking whitespace variants in tokenizer and
wrapping tests

## Testing

- `cargo test -p editor rewrap::tests`

Release Notes:

- Fixed rewrap breaking lines at non-breaking spaces.

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Co-authored-by: Nathan Sobo <nathan@zed.dev>