Add a test for remote tool use by the agent (#30289)

- Adds a new smoke test for the use of the read_file tool by the agent
in an SSH project
- Fixes the SSH shutdown sequence to use a timer from the app's executor
instead of always using a real timer
- Changes the main executor loop for tests to advance the clock
automatically instead of panicking with `parked with nothing left to
run` when there is a delayed task

Release Notes:

- N/A

crates/assistant_tools/src/assistant_tools.rs

@@ -40,13 +40,12 @@ use crate::find_path_tool::FindPathTool;
 use crate::grep_tool::GrepTool;
 use crate::list_directory_tool::ListDirectoryTool;
 use crate::now_tool::NowTool;
-use crate::read_file_tool::ReadFileTool;
 use crate::thinking_tool::ThinkingTool;
 
 pub use edit_file_tool::EditFileToolInput;
 pub use find_path_tool::FindPathToolInput;
 pub use open_tool::OpenTool;
-pub use read_file_tool::ReadFileToolInput;
+pub use read_file_tool::{ReadFileTool, ReadFileToolInput};
 pub use terminal_tool::TerminalTool;
 
 pub fn init(http_client: Arc<HttpClientWithUrl>, cx: &mut App) {