Add button disable on submit for login grant

Signed-off-by: Lukas Döllerer <info@lukas-doellerer.de>

core/js/login/grant.js

@@ -6,5 +6,6 @@ document.querySelector('form').addEventListener('submit', function(e) {
 	wrapper.getElementsByClassName('icon-confirm-white').forEach(function(el) {
 		el.classList.remove('icon-confirm-white')
 		el.classList.add(OCA.Theming && OCA.Theming.inverted ? 'icon-loading-small' : 'icon-loading-small-dark')
+		el.disabled = true
 	})
 })