Settings refactor (#38367)

Co-Authored-By: Ben K <ben@zed.dev>
Co-Authored-By: Anthony <anthony@zed.dev>
Co-Authored-By: Mikayla <mikayla@zed.dev>

Release Notes:

- settings: Major internal changes to settings. The primary user-facing
effect is that some settings which did not make sense in project
settings files are no-longer read from there. (For example the inline
blame settings)

---------

Co-authored-by: Ben Kunkle <ben@zed.dev>
Co-authored-by: Mikayla Maki <mikayla.c.maki@gmail.com>
Co-authored-by: Anthony <anthony@zed.dev>

crates/image_viewer/src/image_viewer_settings.rs

@@ -1,40 +1,30 @@
 use gpui::App;
-use schemars::JsonSchema;
-use serde::{Deserialize, Serialize};
-use settings::{Settings, SettingsKey, SettingsSources, SettingsUi};
+pub use settings::ImageFileSizeUnit;
+use settings::Settings;
+use util::MergeFrom;
 
 /// The settings for the image viewer.
-#[derive(Clone, Debug, Serialize, Deserialize, JsonSchema, Default, SettingsUi, SettingsKey)]
-#[settings_key(key = "image_viewer")]
+#[derive(Clone, Debug, Default)]
 pub struct ImageViewerSettings {
     /// The unit to use for displaying image file sizes.
     ///
     /// Default: "binary"
-    #[serde(default)]
     pub unit: ImageFileSizeUnit,
 }
 
-#[derive(Clone, Copy, Debug, Serialize, Deserialize, JsonSchema, Default)]
-#[serde(rename_all = "snake_case")]
-pub enum ImageFileSizeUnit {
-    /// Displays file size in binary units (e.g., KiB, MiB).
-    #[default]
-    Binary,
-    /// Displays file size in decimal units (e.g., KB, MB).
-    Decimal,
-}
-
 impl Settings for ImageViewerSettings {
-    type FileContent = Self;
-
-    fn load(sources: SettingsSources<Self::FileContent>, _: &mut App) -> anyhow::Result<Self> {
-        SettingsSources::<Self::FileContent>::json_merge_with(
-            [sources.default]
-                .into_iter()
-                .chain(sources.user)
-                .chain(sources.server),
-        )
+    fn from_defaults(content: &settings::SettingsContent, _cx: &mut App) -> Self {
+        Self {
+            unit: content.image_viewer.clone().unwrap().unit.unwrap(),
+        }
     }
 
-    fn import_from_vscode(_vscode: &settings::VsCodeSettings, _current: &mut Self::FileContent) {}
+    fn refine(&mut self, content: &settings::SettingsContent, _cx: &mut App) {
+        self.unit.merge_from(
+            &content
+                .image_viewer
+                .as_ref()
+                .and_then(|image_viewer| image_viewer.unit),
+        );
+    }
 }