Don't display no contacts screen when search returns no results

src/main/kotlin/org/briarproject/briar/desktop/contact/ContactsViewModel.kt

@@ -43,6 +43,10 @@ abstract class ContactsViewModel(
 
     private val _fullContactList = mutableStateListOf<BaseContactItem>()
 
+    val noContactsYet = derivedStateOf {
+        _fullContactList.isEmpty()
+    }
+
     val contactList = derivedStateOf {
         _fullContactList.filter(::filterContactItem).sortedByDescending { it.timestamp }
     }

src/main/kotlin/org/briarproject/briar/desktop/conversation/PrivateMessageScreen.kt

@@ -46,7 +46,7 @@ fun PrivateMessageScreen(
     var isContactDialogVisible by remember { mutableStateOf(false) }
     if (isContactDialogVisible) AddContactDialog(onClose = { isContactDialogVisible = false })
 
-    if (viewModel.contactList.value.isEmpty()) {
+    if (viewModel.noContactsYet.value) {
         NoContactsYet(onContactAdd = { isContactDialogVisible = true })
         return
     }