Add find-replace-file tool, use it by default over edit-files-tool (#27438)

@agu-z and paired on trying out a "one tool call per edit" approach for
editing files. (The previous approach is still available, it's just
unchecked by default for now.)

Release Notes:

- N/A

---------

Co-authored-by: Agus <agus@zed.dev>

crates/assistant_tools/src/edit_files_tool.rs

@@ -1,7 +1,7 @@
 mod edit_action;
 pub mod log;
-mod replace;
 
+use crate::replace::{replace_exact, replace_with_flexible_indent};
 use anyhow::{anyhow, Context, Result};
 use assistant_tool::{ActionLog, Tool};
 use collections::HashSet;
@@ -13,7 +13,6 @@ use language_model::{
 };
 use log::{EditToolLog, EditToolRequestId};
 use project::Project;
-use replace::{replace_exact, replace_with_flexible_indent};
 use schemars::JsonSchema;
 use serde::{Deserialize, Serialize};
 use std::fmt::Write;