[TIMOB-14120] Cloud: Use the ACS endpoint defined in tiapp.xml

This pull request enables the specification of full urls (such as https://api.clould.appclerator.com) for the acs-base-url and acs-authbase-url properties in tiapp.xml. All references to useSecure have been removed since using http or https is determined by the specified URL. The anvil tests have not been updated to reflect this removal in order to ensure compatibility with existing code which still may set this property.