tab: Add setting to hide the close button entirely (#23880)

Closes #23744

Release Notes:

- Changed the `always_show_close_button` key to `show_close_button` and
introduced a new `hidden` value, that allows never displaying the close
button.

---------

Co-authored-by: Peter Tripp <peter@zed.dev>
Co-authored-by: Danilo Leal <daniloleal09@gmail.com>
Co-authored-by: smit <0xtimsb@gmail.com>

crates/workspace/src/item.rs

@@ -42,7 +42,7 @@ pub struct ItemSettings {
     pub activate_on_close: ActivateOnClose,
     pub file_icons: bool,
     pub show_diagnostics: ShowDiagnostics,
-    pub always_show_close_button: bool,
+    pub show_close_button: ShowCloseButton,
 }
 
 #[derive(Deserialize)]
@@ -60,6 +60,15 @@ pub enum ClosePosition {
     Right,
 }
 
+#[derive(Clone, Default, Serialize, Deserialize, JsonSchema)]
+#[serde(rename_all = "lowercase")]
+pub enum ShowCloseButton {
+    Always,
+    #[default]
+    Hover,
+    Hidden,
+}
+
 #[derive(Copy, Clone, Debug, Default, Serialize, Deserialize, JsonSchema, PartialEq, Eq)]
 #[serde(rename_all = "snake_case")]
 pub enum ShowDiagnostics {
@@ -104,7 +113,7 @@ pub struct ItemSettingsContent {
     /// Whether to always show the close button on tabs.
     ///
     /// Default: false
-    always_show_close_button: Option<bool>,
+    show_close_button: Option<ShowCloseButton>,
 }
 
 #[derive(Clone, Default, Serialize, Deserialize, JsonSchema)]