qt: Make "Create new receiving address" default unconditionally

This change makes this button visually accented, and gives to users a
hint about the primary action.
This commit does not change behavior.

src/qt/forms/receivecoinsdialog.ui

@@ -114,6 +114,12 @@
              <iconset resource="../bitcoin.qrc">
               <normaloff>:/icons/receiving_addresses</normaloff>:/icons/receiving_addresses</iconset>
             </property>
+            <property name="autoDefault">
+             <bool>false</bool>
+            </property>
+            <property name="default">
+             <bool>true</bool>
+            </property>
            </widget>
           </item>
           <item>