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/language/src/language_settings.rs

@@ -450,6 +450,11 @@ pub struct IndentGuideSettings {
     /// Default: 1
     #[serde(default = "line_width")]
     pub line_width: u32,
+    /// The width of the active indent guide in pixels, between 1 and 10.
+    ///
+    /// Default: 1
+    #[serde(default = "active_line_width")]
+    pub active_line_width: u32,
     /// Determines how indent guides are colored.
     ///
     /// Default: Fixed
@@ -466,6 +471,10 @@ fn line_width() -> u32 {
     1
 }
 
+fn active_line_width() -> u32 {
+    line_width()
+}
+
 /// Determines how indent guides are colored.
 #[derive(Default, Debug, Copy, Clone, PartialEq, Eq, Serialize, Deserialize, JsonSchema)]
 #[serde(rename_all = "snake_case")]