Add a setting to increase the thickness of the active indent guide (#13210)

Resolves #12312.

Release Notes:

- Added an option to configure the line width of the active indent guide
[#12312](https://github.com/zed-industries/zed/issues/12312)

crates/editor/src/editor_tests.rs

@@ -11808,6 +11808,7 @@ fn indent_guide(buffer_id: BufferId, start_row: u32, end_row: u32, depth: u32) -
         settings: IndentGuideSettings {
             enabled: true,
             line_width: 1,
+            active_line_width: 1,
             ..Default::default()
         },
     }