chore: Replace as_any functions with trait upcasting (#28221)

Closes #ISSUE

Release Notes:

- N/A

crates/git_ui/src/commit_view.rs

@@ -244,10 +244,6 @@ impl language::File for GitBlob {
         self.worktree_id
     }
 
-    fn as_any(&self) -> &dyn Any {
-        self
-    }
-
     fn to_proto(&self, _cx: &App) -> language::proto::File {
         unimplemented!()
     }
@@ -282,10 +278,6 @@ impl language::File for CommitMetadataFile {
         self.worktree_id
     }
 
-    fn as_any(&self) -> &dyn Any {
-        self
-    }
-
     fn to_proto(&self, _: &App) -> language::proto::File {
         unimplemented!()
     }