settings_ui: Collect all settings files (#38816)

Closes #ISSUE

Updates the settings editor to collect all known settings files from the
settings store, in order to show them in the UI. Additionally adds a
fake worktree instantiation in the settings UI example binary in order
to have more than one file available when testing.

Release Notes:

- N/A *or* Added/Fixed/Improved ...

crates/settings/src/settings.rs

@@ -24,7 +24,8 @@ pub use keymap_file::{
 pub use settings_file::*;
 pub use settings_json::*;
 pub use settings_store::{
-    InvalidSettingsError, LocalSettingsKind, Settings, SettingsKey, SettingsLocation, SettingsStore,
+    InvalidSettingsError, LocalSettingsKind, Settings, SettingsFile, SettingsKey, SettingsLocation,
+    SettingsStore,
 };
 
 pub use vscode_import::{VsCodeSettings, VsCodeSettingsSource};

crates/settings/src/settings_store.rs

@@ -156,6 +156,16 @@ pub struct SettingsStore {
         mpsc::UnboundedSender<Box<dyn FnOnce(AsyncApp) -> LocalBoxFuture<'static, Result<()>>>>,
 }
 
+#[derive(Clone, PartialEq)]
+pub enum SettingsFile {
+    User,
+    Global,
+    Extension,
+    Server,
+    Default,
+    Local((WorktreeId, Arc<Path>)),
+}
+
 #[derive(Clone)]
 pub struct Editorconfig {
     pub is_root: bool,
@@ -479,6 +489,36 @@ impl SettingsStore {
             })
         })
     }
+
+    pub fn get_all_files(&self) -> Vec<SettingsFile> {
+        let mut files = Vec::from_iter(
+            self.local_settings
+                .keys()
+                // rev because these are sorted by path, so highest precedence is last
+                .rev()
+                .cloned()
+                .map(SettingsFile::Local),
+        );
+
+        if self.server_settings.is_some() {
+            files.push(SettingsFile::Server);
+        }
+        // ignoring profiles
+        // ignoring os profiles
+        // ignoring release channel profiles
+
+        if self.user_settings.is_some() {
+            files.push(SettingsFile::User);
+        }
+        if self.extension_settings.is_some() {
+            files.push(SettingsFile::Extension);
+        }
+        if self.global_settings.is_some() {
+            files.push(SettingsFile::Global);
+        }
+        files.push(SettingsFile::Default);
+        files
+    }
 }
 
 impl SettingsStore {