migrator: Add migration for settings changed prior to migrator-introduction (#27375)

This PR updates two existing settings to use the settings migrator
instead of a manually implemented visitor. Both of these settings were
changed prior to the introduction of automatic migrations and the
visitor ensured that the settings were kept backwards compatible. See
https://github.com/zed-industries/zed/pull/22200 and
https://github.com/zed-industries/zed/pull/22364 respectively.

WIth this change, existing user configurations are updated accordingly
and the corresponding settings can derive `Deserialize` again.

I also added tests for the replacement of settings values, as there was
no test for this behaviour. Additionally, I added a seperate test for
the existing migration of `always_show_close_button`, since that
migration updated both the key and value.

Release Notes:

- N/A

crates/migrator/src/migrator.rs

@@ -104,6 +104,10 @@ pub fn migrate_keymap(text: &str) -> Result<Option<String>> {
 
 pub fn migrate_settings(text: &str) -> Result<Option<String>> {
     let migrations: &[(MigrationPatterns, &Query)] = &[
+        (
+            migrations::m_2025_01_02::SETTINGS_PATTERNS,
+            &SETTINGS_QUERY_2025_01_02,
+        ),
         (
             migrations::m_2025_01_29::SETTINGS_PATTERNS,
             &SETTINGS_QUERY_2025_01_29,
@@ -166,6 +170,10 @@ define_query!(
 );
 
 // settings
+define_query!(
+    SETTINGS_QUERY_2025_01_02,
+    migrations::m_2025_01_02::SETTINGS_PATTERNS
+);
 define_query!(
     SETTINGS_QUERY_2025_01_29,
     migrations::m_2025_01_29::SETTINGS_PATTERNS
@@ -461,4 +469,54 @@ mod tests {
             ),
         )
     }
+
+    #[test]
+    fn test_replace_settings_value() {
+        assert_migrate_settings(
+            r#"
+                {
+                    "scrollbar": {
+                        "diagnostics": true
+                    },
+                    "chat_panel": {
+                        "button": true
+                    }
+                }
+            "#,
+            Some(
+                r#"
+                {
+                    "scrollbar": {
+                        "diagnostics": "all"
+                    },
+                    "chat_panel": {
+                        "button": "always"
+                    }
+                }
+            "#,
+            ),
+        )
+    }
+
+    #[test]
+    fn test_replace_settings_name_and_value() {
+        assert_migrate_settings(
+            r#"
+                {
+                    "tabs": {
+                        "always_show_close_button": true
+                    }
+                }
+            "#,
+            Some(
+                r#"
+                {
+                    "tabs": {
+                        "show_close_button": "always"
+                    }
+                }
+            "#,
+            ),
+        )
+    }
 }