CRM-12696 fix: re-structured CRM_Contact_Form_Edit_Address::fixStateSele...

Previously, country address option was neccessary to be enabled for county selection(which actually depends on state).

So, after this re-structuring, even if country address field is disabled in civi, selecting state and corresponding county will be possible accross various civicrm forms i.e. profiles, contact add/edit, online contribution profiles, online event profiles, batch updates, pcp account form, etc.