Rust 1.78 (#11314)

Notable things I've had to fix due to 1.78:
- Better detection of unused items
- New clippy lint (`assigning_clones`) that points out places where assignment operations with clone rhs could be replaced with more performant `clone_into`
Release Notes:

- N/A

crates/live_kit_server/build.rs

@@ -1,5 +1,6 @@
 fn main() {
     prost_build::Config::new()
+        .type_attribute("SendDataResponse", "#[allow(clippy::empty_docs)]")
         .compile_protos(&["protocol/livekit_room.proto"], &["protocol"])
         .unwrap();
 }