Start on adding support for editing via the assistant panel (#14795)

Note that this shouldn't have any visible user-facing behavior yet. The
feature is incomplete but we wanna merge early to avoid a long-running
branch.

Release Notes:

- N/A

---------

Co-authored-by: Nathan <nathan@zed.dev>

crates/assistant/src/assistant.rs

@@ -7,7 +7,6 @@ mod inline_assistant;
 mod model_selector;
 mod prompt_library;
 mod prompts;
-mod search;
 mod slash_command;
 mod streaming_diff;
 mod terminal_inline_assistant;
@@ -53,9 +52,9 @@ actions!(
         InsertActivePrompt,
         DeployHistory,
         DeployPromptLibrary,
-        ApplyEdit,
         ConfirmCommand,
-        ToggleModelSelector
+        ToggleModelSelector,
+        DebugEditSteps
     ]
 );