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/editor/src/rust_analyzer_ext.rs

@@ -113,6 +113,7 @@ pub fn expand_macro_recursively(
                     cx.new_view(|cx| Editor::for_multibuffer(multibuffer, Some(project), true, cx)),
                 ),
                 None,
+                true,
                 cx,
             );
         })