display error page if page load fails
Created by: balcy
ErrorSheet: in Browser.qml use the property lastLoadFailed for the binding (was already correct in WebApp.qml)
Browser.qml / WebApp.qml: remove the top margin of the error sheet AddressBar: new lastLoadSucceeded property: show lock symbol only, if last load was successful for https pages
fixes https://github.com/ubports/morph-browser/issues/118
now the chances are high that it fixes https://github.com/ubports/morph-browser/issues/133 as well