bluetooth: Tweak AdwStatusPage design

Some AdwStatusPage changes to follow HIG:

- Apply .suggested-action style class to the button
- Ditch period from the description

- https://developer.gnome.org/hig/patterns/controls/buttons.html
- https://developer.gnome.org/hig/guidelines/writing-style.html

panels/bluetooth/cc-bluetooth-panel.ui

@@ -29,14 +29,14 @@
           <object class="AdwStatusPage" id="disabled_page">
             <property name="icon-name">bluetooth-active-symbolic</property>
             <property name="title" translatable="yes">Bluetooth Turned Off</property>
-            <property name="description" translatable="yes">Turn on to connect devices and receive file transfers.</property>
+            <property name="description" translatable="yes">Turn on to connect devices and receive file transfers</property>
           </object>
         </child>
         <child>
           <object class="AdwStatusPage" id="airplane_page">
             <property name="icon-name">airplane-mode-symbolic</property>
             <property name="title" translatable="yes">Airplane Mode is On</property>
-            <property name="description" translatable="yes">Bluetooth is disabled when airplane mode is on.</property>
+            <property name="description" translatable="yes">Bluetooth is disabled when airplane mode is on</property>
             <property name="child">
               <object class="GtkButton">
                 <property name="label" translatable="yes">Turn Off Airplane Mode</property>
@@ -45,6 +45,7 @@
                 <signal name="clicked" handler="airplane_mode_off_button_clicked_cb" object="CcBluetoothPanel" swapped="yes"/>
                 <style>
                   <class name="pill"/>
+                  <class name="suggested-action"/>
                 </style>
               </object>
             </property>