add option to choose from unrelated keys

OpenKeychain/src/main/res/menu/select_identity_menu.xml

@@ -2,7 +2,6 @@
 <menu xmlns:android="http://schemas.android.com/apk/res/android">
     <item
         android:id="@+id/list_all_keys"
-        android:title="List all keys"
-        android:checkable="true"
+        android:title="@string/menu_list_unrelated_keys"
         android:orderInCategory="1" />
 </menu>

OpenKeychain/src/main/res/values/strings.xml

@@ -1995,4 +1995,5 @@
     <string name="select_identity_cancel">Cancel</string>
     <string name="select_identity_create">Create a key for me</string>
     <string name="error_save_key_internal">"Internal error saving key!"</string>
+    <string name="menu_list_unrelated_keys">List unrelated keys</string>
 </resources>