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/symbols_command.rs

@@ -3,7 +3,7 @@ use anyhow::{anyhow, Context as _, Result};
 use assistant_slash_command::{ArgumentCompletion, SlashCommandOutputSection};
 use editor::Editor;
 use gpui::{Task, WeakView};
-use language::LspAdapterDelegate;
+use language::{BufferSnapshot, LspAdapterDelegate};
 use std::sync::Arc;
 use std::{path::Path, sync::atomic::AtomicBool};
 use ui::{IconName, WindowContext};
@@ -41,6 +41,8 @@ impl SlashCommand for OutlineSlashCommand {
     fn run(
         self: Arc<Self>,
         _arguments: &[String],
+        _context_slash_command_output_sections: &[SlashCommandOutputSection<language::Anchor>],
+        _context_buffer: BufferSnapshot,
         workspace: WeakView<Workspace>,
         _delegate: Option<Arc<dyn LspAdapterDelegate>>,
         cx: &mut WindowContext,
@@ -77,6 +79,7 @@ impl SlashCommand for OutlineSlashCommand {
                         range: 0..outline_text.len(),
                         icon: IconName::ListTree,
                         label: path.to_string_lossy().to_string().into(),
+                        metadata: None,
                     }],
                     text: outline_text,
                     run_commands_in_text: false,