Made changes to menu items in WifiSettings and AccountSyncSettings.

When the admin has set disallow_config_wifi, menu items are not added.
we need to check if the menu items can be added after this fragment is
resumed. And for remove account menuitem, check whether any admin has
disabled management of a specific account type.

Change-Id: I58f5a59fe0614c9bc7068b15f43f89527939359d