[FIX] web_editor: add focus in url input of link dialog

Before this commit, when clicking on the link button after focusing a
link, the first input of the link dialog was hidden (label), and the
second input (URL) was not focused.

In this commit, we focus the first *visible* input so users are able to
directly copy-paste URL.

task-2083209

closes odoo/odoo#44931

Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>

addons/web_editor/static/src/js/wysiwyg/widgets/dialog.js

@@ -36,7 +36,7 @@ var SummernoteDialog = Dialog.extend({
 
         var self = this;
         this.opened(function () {
-            self.$('input:first').focus();
+            self.$('input:visible:first').focus();
             self.$el.closest('.modal').addClass('o_web_editor_dialog');
             self.$el.closest('.modal').on('hidden.bs.modal', self.options.onClose);
         });