Add a setting to control the number of context lines in excerpts (#37138)

Fixes https://github.com/zed-industries/zed/discussions/28739

Release Notes:

- Added a setting, `excerpt_context_lines`, for setting the number of
context lines shown in a multibuffer
c3ccdc0b44Mikayla Maki committed on 8/29/2025, 3:50:24 AM· committed by GitHubparente5cea54
15 files changedLine totals unavailable