agent: Migrate tool names in settings (#29168)

Release Notes:

- agent: Add migration to rename `find_replace_file` tool to
`edit_file`, and `regex_search` to `grep`.

crates/migrator/src/migrations/m_2025_04_21/settings.rs

@@ -0,0 +1,25 @@
+use std::ops::Range;
+use tree_sitter::{Query, QueryMatch};
+
+use crate::MigrationPatterns;
+use crate::patterns::SETTINGS_ASSISTANT_TOOLS_PATTERN;
+
+pub const SETTINGS_PATTERNS: MigrationPatterns =
+    &[(SETTINGS_ASSISTANT_TOOLS_PATTERN, rename_tools)];
+
+fn rename_tools(contents: &str, mat: &QueryMatch, query: &Query) -> Option<(Range<usize>, String)> {
+    let tool_name_capture_ix = query.capture_index_for_name("tool_name")?;
+    let tool_name_range = mat
+        .nodes_for_capture_index(tool_name_capture_ix)
+        .next()?
+        .byte_range();
+    let tool_name = contents.get(tool_name_range.clone())?;
+
+    let new_name = match tool_name {
+        "find_replace_file" => "edit_file",
+        "regex_search" => "grep",
+        _ => return None,
+    };
+
+    Some((tool_name_range, new_name.to_string()))
+}