move rename to a new mod

crates/ra_ide_api/src/lib.rs

@@ -23,6 +23,7 @@ mod hover;
 mod call_info;
 mod syntax_highlighting;
 mod parent_module;
+mod rename;
 
 use std::{fmt, sync::Arc};
 
@@ -464,7 +465,7 @@ impl Analysis {
         &self,
         position: FilePosition,
         new_name: &str,
-    ) -> Cancelable<Vec<SourceFileEdit>> {
+    ) -> Cancelable<Option<SourceChange>> {
         self.with_db(|db| db.rename(position, new_name))
     }