pending message: use the warning color and show a spinner

Show the warning color so the user doesn't just ignore the page and closes it,
since it could indicate that something went wrong.

And to make it clear that the page is waiting on new information from the backend
show a small spinner.

src/dbp-mono-processpayment.js

@@ -1213,16 +1213,16 @@ class DbpMonoProcessPayment extends ScopedElementsMixin(DBPMonoLitElement) {
                 </div>
 
                 <div class="${classMap({hidden: !this.showPending || this.modalIsVisible})}">
-                    <dbp-inline-notification type="info">
+                    <dbp-inline-notification type="warning">
                         <div slot="body">
-                            <p>${i18n.t('pending.info')}</p>
+                            <p><dbp-mini-spinner text=" "></dbp-mini-spinner> ${i18n.t('pending.info')}</p>
                             <p>
                                 ${i18n.t('pending.info-canceled', {
                                     'return-name': this.returnHostname,
                                 })}
                             </p>
                             <dbp-button
-                                type="is-info"
+                                type="is-warning"
                                 no-spinner-on-click
                                 @click="${() => {
                                     window.location.href = this.returnUrl;