support keyword-based mentions in tidy

Author: RalfJung

src/tools/tidy/src/triagebot.rs

@@ -19,7 +19,12 @@ pub fn check(path: &Path, bad: &mut bool) {
 
     // Check [mentions."*"] sections, i.e. [mentions."compiler/rustc_const_eval/src/"]
     if let Some(Value::Table(mentions)) = config.get("mentions") {
-        for path_str in mentions.keys() {
+        for (entry_key, entry_val) in mentions.iter() {
+            // If the type is set to something other than "filename", then this is not a path.
+            if entry_val.get("type").is_some_and(|t| t.as_str().unwrap_or_default() != "filename") {
+                continue;
+            }
+            let path_str = entry_key;
             // Remove quotes from the path
             let clean_path = path_str.trim_matches('"');
             let full_path = path.join(clean_path);