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/auto_command.rs

@@ -1,7 +1,7 @@
 use super::create_label_for_command;
 use super::{SlashCommand, SlashCommandOutput};
 use anyhow::{anyhow, Result};
-use assistant_slash_command::ArgumentCompletion;
+use assistant_slash_command::{ArgumentCompletion, SlashCommandOutputSection};
 use feature_flags::FeatureFlag;
 use futures::StreamExt;
 use gpui::{AppContext, AsyncAppContext, Task, WeakView};
@@ -87,6 +87,8 @@ impl SlashCommand for AutoCommand {
     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,