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/language/src/language.rs

@@ -1126,7 +1126,7 @@ impl Language {
                 for setting in query.property_settings(ix) {
                     match setting.key.as_ref() {
                         "language" => {
-                            config.language = setting.value.clone();
+                            config.language.clone_from(&setting.value);
                         }
                         "combined" => {
                             config.combined = true;