refactor(messages): add back button

app/src/main/java/com/geeksville/mesh/ui/MessagesFragment.kt

@@ -242,6 +242,10 @@ class MessagesFragment : Fragment(), Logging {
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         super.onViewCreated(view, savedInstanceState)
 
+        binding.toolbar.setNavigationOnClickListener {
+            parentFragmentManager.popBackStack()
+        }
+
         setFragmentResultListener("requestKey") { _, bundle->
             // get the result from bundle
             contactKey = bundle.getString("contactKey").toString()

app/src/main/res/layout/messages_fragment.xml

@@ -1,7 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto"
-    xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     android:background="@color/colorAdvancedBackground">
@@ -13,7 +12,8 @@
         android:layout_width="match_parent"
         android:layout_height="?attr/actionBarSize"
         android:background="@color/colorPrimary"
-        app:layout_constraintTop_toTopOf="parent">
+        app:layout_constraintTop_toTopOf="parent"
+        app:navigationIcon="?android:attr/homeAsUpIndicator">
 
         <androidx.constraintlayout.widget.ConstraintLayout
             android:layout_width="match_parent"
@@ -41,7 +41,7 @@
         app:layout_constraintBottom_toTopOf="@+id/quickChatView"
         app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintStart_toStartOf="parent"
-        app:layout_constraintTop_toBottomOf="@id/toolbar" >
+        app:layout_constraintTop_toBottomOf="@id/toolbar">
 
     </androidx.recyclerview.widget.RecyclerView>
 
@@ -58,7 +58,7 @@
 
         <LinearLayout
             android:id="@+id/quickChatLayout"
-            android:layout_width="match_parent"
+            android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:orientation="horizontal" />
     </HorizontalScrollView>