Refactor markdown formatting utilities to avoid building intermediate strings (#29511)

These were nearly always used when using `format!` / `write!` etc, so it
makes sense to not have an intermediate `String`.

Release Notes:

- N/A

crates/assistant_tools/src/fetch_tool.rs

@@ -14,7 +14,7 @@ use project::Project;
 use schemars::JsonSchema;
 use serde::{Deserialize, Serialize};
 use ui::IconName;
-use util::markdown::MarkdownString;
+use util::markdown::MarkdownEscaped;
 
 #[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Clone, Copy)]
 enum ContentType {
@@ -134,7 +134,7 @@ impl Tool for FetchTool {
 
     fn ui_text(&self, input: &serde_json::Value) -> String {
         match serde_json::from_value::<FetchToolInput>(input.clone()) {
-            Ok(input) => format!("Fetch {}", MarkdownString::escape(&input.url)),
+            Ok(input) => format!("Fetch {}", MarkdownEscaped(&input.url)),
             Err(_) => "Fetch URL".to_string(),
         }
     }