Reduce amount of allocations in RustLsp label handling (#35786)

There can be a lot of completions after all


Release Notes:

- N/A

crates/rope/src/rope.rs

@@ -471,11 +471,19 @@ impl<'a> FromIterator<&'a str> for Rope {
 }
 
 impl From<String> for Rope {
+    #[inline(always)]
     fn from(text: String) -> Self {
         Rope::from(text.as_str())
     }
 }
 
+impl From<&String> for Rope {
+    #[inline(always)]
+    fn from(text: &String) -> Self {
+        Rope::from(text.as_str())
+    }
+}
+
 impl fmt::Display for Rope {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         for chunk in self.chunks() {