CLOSES: #50002 

When using indent-based folding (the default, `document_folding_ranges =
Off`),
collapsed folds in brace-delimited languages displayed the closing
delimiter on
a separate line:

fn b() {⋯
}

This extends the fold range in `crease_for_buffer_row` to include the
trailing
newline and leading whitespace before a closing `}`, `)`, or `]`,
producing
the expected single-line display:

fn b() {⋯}

Whitespace-sensitive languages like Python are unaffected — their
terminating
lines don't start with a closing delimiter, so the existing behavior is
preserved.

Before you mark this PR as ready for review, make sure that you have:
- [x] Added a solid test coverage and/or screenshots from doing manual
testing
- [x] Done a self-review taking into account security and performance
aspects
- [x] Aligned any UI changes with the [UI
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)

Screenshots:
Before:
<img width="676" height="584" alt="image"
src="https://github.com/user-attachments/assets/0779233b-e287-495a-bab4-d2a97829e1c0"
/>


After:
<img width="1498" height="824" alt="image"
src="https://github.com/user-attachments/assets/ec6b4cb0-dac1-4db0-beed-38131a27b5c8"
/>



Release Notes:

- Fixed indent-based code folding to display the closing delimiter (`}`,
`)`, `]`) on the same line as the fold placeholder instead of on a
separate line
([#50002](https://github.com/zed-industries/zed/issues/50002)).