Add plumbing for new message/reply through core, gtk, and osx

core/kordophone-db/src/tests/mod.rs

@@ -26,7 +26,7 @@ fn participants_vec_equal_ignoring_id(a: &[Participant], b: &[Participant]) -> b
     // For each participant in a, check if there is a matching participant in b
     a.iter().all(|a_participant| {
         b.iter().any(|b_participant| participants_equal_ignoring_id(a_participant, b_participant))
-    }) && 
+    }) &&
     // Also check the reverse to ensure no duplicates
     b.iter().all(|b_participant| {
         a.iter().any(|a_participant| participants_equal_ignoring_id(b_participant, a_participant))