Cleanup: Use ModifierState enum in input.rs in sticky keys filter

Test: none
Bug: 245989146
Change-Id: If2c46c9fb228ebb35bc7c66a4d58bf27ec000f4b
diff --git a/libs/input/rust/input.rs b/libs/input/rust/input.rs
index 72b421c..0574245 100644
--- a/libs/input/rust/input.rs
+++ b/libs/input/rust/input.rs
@@ -272,7 +272,7 @@
 
 bitflags! {
     /// Modifier state flags
-    #[derive(Debug, PartialEq)]
+    #[derive(Default, Debug, Copy, Clone, Eq, PartialEq)]
     pub struct ModifierState: u32 {
         /// No meta keys are pressed
         const None = input_bindgen::AMETA_NONE;