Improve code folding to exclude folding line breaks in whitespace-sensitive languages (#13108)

<img width="1219" alt="Screenshot 2024-06-16 at 15 43 31"
src="https://github.com/zed-industries/zed/assets/87859239/dd05de16-7f20-4c88-9e95-021555b8b78b">
<img width="1219" alt="Screenshot 2024-06-16 at 15 45 10"
src="https://github.com/zed-industries/zed/assets/87859239/b1b78cdd-f34d-4ea3-9728-4741727a9643">

Updated the foldable_range method to exclude folding line breaks during
code folding in whitespace-sensitive languages like Python and YAML.
This adjustment ensures that folding behaves as expected, similar to
other code editors.

Ref #11614

Release Notes:

- Improved code folds to ignore trailing newlines