Rename regex search tool to grep and accept an include glob pattern (#29100)

This PR renames the `regex_search` tool to `grep` because I think it
conveys more meaning to the model, the idea of searching the filesystem
with a regular expression. It's also one word and the model seems to be
using it effectively after some additional prompt tuning.

It also takes an include pattern to filter on the specific files we try
to search. I'd like to encourage the model to scope its searches more
aggressively, as in my testing, I'm only seeing it filter on file
extension.

Release Notes:

- N/A

crates/assistant_tools/src/assistant_tools.rs

@@ -9,13 +9,13 @@ mod delete_path_tool;
 mod diagnostics_tool;
 mod edit_file_tool;
 mod fetch_tool;
+mod grep_tool;
 mod list_directory_tool;
 mod move_path_tool;
 mod now_tool;
 mod open_tool;
 mod path_search_tool;
 mod read_file_tool;
-mod regex_search_tool;
 mod rename_tool;
 mod replace;
 mod schema;
@@ -44,12 +44,12 @@ use crate::delete_path_tool::DeletePathTool;
 use crate::diagnostics_tool::DiagnosticsTool;
 use crate::edit_file_tool::EditFileTool;
 use crate::fetch_tool::FetchTool;
+use crate::grep_tool::GrepTool;
 use crate::list_directory_tool::ListDirectoryTool;
 use crate::now_tool::NowTool;
 use crate::open_tool::OpenTool;
 use crate::path_search_tool::PathSearchTool;
 use crate::read_file_tool::ReadFileTool;
-use crate::regex_search_tool::RegexSearchTool;
 use crate::rename_tool::RenameTool;
 use crate::symbol_info_tool::SymbolInfoTool;
 use crate::terminal_tool::TerminalTool;
@@ -77,7 +77,7 @@ pub fn init(http_client: Arc<HttpClientWithUrl>, cx: &mut App) {
     registry.register_tool(ContentsTool);
     registry.register_tool(PathSearchTool);
     registry.register_tool(ReadFileTool);
-    registry.register_tool(RegexSearchTool);
+    registry.register_tool(GrepTool);
     registry.register_tool(RenameTool);
     registry.register_tool(ThinkingTool);
     registry.register_tool(FetchTool::new(http_client));