Fix for U4-5564

If umbracoUseSSL is set to true, change makes GetCurrentServerUmbracoBaseUrl() return HTTPS URL.  Also overrides ApplicationContext.Current.OriginalRequestUrl to use Port 443 instead of originally loaded port.
Yes, that base url doesn't specify scheme but you can have a port in there if you need to like: helloworld.com:1234/umbraco

when UseSSL is true, the logic in ServerEnvironmentHelper.GetCurrentServerUmbracoBaseUrl is what sets http vs https

but if you are running on 443, there's no need to specify a port.