treewide: Parent from AdwBin where possible

Part-of: <https://gitlab.gnome.org/GNOME/calls/-/merge_requests/714>

src/ui/call-selector-item.ui

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <interface>
   <requires lib="gtk" version="4.0"/>
-  <template class="CallsCallSelectorItem" parent="GtkBox">
+  <template class="CallsCallSelectorItem" parent="AdwBin">
     <child>
       <object class="GtkFrame">
         <property name="child">

src/ui/contacts-box.ui

@@ -2,7 +2,7 @@
 <interface>
   <requires lib="gtk" version="4.0"/>
   <requires lib="libadwaita" version="0.0"/>
-  <template class="CallsContactsBox" parent="GtkWidget">
+  <template class="CallsContactsBox" parent="AdwBin">
     <child>
       <object class="GtkScrolledWindow" id="child">
         <property name="hexpand">True</property>

src/ui/history-box.ui

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <interface>
   <requires lib="gtk" version="4.0"/>
-  <template class="CallsHistoryBox" parent="GtkWidget">
+  <template class="CallsHistoryBox" parent="AdwBin">
     <child>
       <object class="GtkStack" id="stack">
         <property name="hexpand">True</property>

src/ui/new-call-box.ui

@@ -2,7 +2,7 @@
 <interface>
   <requires lib="gtk" version="4.0"/>
   <requires lib="libadwaita" version="1.0"/>
-  <template class="CallsNewCallBox" parent="GtkWidget">
+  <template class="CallsNewCallBox" parent="AdwBin">
     <child>
       <object class="GtkBox" id="child">
         <property name="margin-start">24</property>