Introduce a new /delta command (#17903)

Release Notes:

- Added a new `/delta` command to re-insert changed files that were
previously included in a context.

---------

Co-authored-by: Roy <roy@anthropic.com>

crates/assistant/src/slash_command/search_command.rs

@@ -60,6 +60,8 @@ impl SlashCommand for SearchSlashCommand {
     fn run(
         self: Arc<Self>,
         arguments: &[String],
+        _context_slash_command_output_sections: &[SlashCommandOutputSection<language::Anchor>],
+        _context_buffer: language::BufferSnapshot,
         workspace: WeakView<Workspace>,
         _delegate: Option<Arc<dyn LspAdapterDelegate>>,
         cx: &mut WindowContext,
@@ -168,6 +170,7 @@ impl SlashCommand for SearchSlashCommand {
                         range: 0..text.len(),
                         icon: IconName::MagnifyingGlass,
                         label: query,
+                        metadata: None,
                     });
 
                     SlashCommandOutput {