Send moved-card notices as Nextcloud notifications too

Each workflow now has a notify channel (mail, notification or both) next
to its recipient mode. Notifications go out per card through
OCP\Notification\IManager, so they show up in the bell and as push on the
mobile and desktop clients. Without the notifications app nothing is sent.
The one-off "workflow disabled" notice is sent as a notification as well.

Existing workflows keep mail (migration Version1004). Bumps to 35.3.0 so
the migration runs.

lib/Service/NotificationMailer.php

@@ -128,6 +128,20 @@ class NotificationMailer {
 		return htmlspecialchars($text, ENT_QUOTES, 'UTF-8');
 	}
 
+	/**
+	 * Completes "… wurde ausgeschaltet, weil %s." — shared with
+	 * Notification\Notifier so mail and notification give the same reason.
+	 *
+	 * @param WorkflowRunner::TARGET_* $brokenTarget
+	 */
+	public static function describeBrokenTarget(string $brokenTarget): string {
+		return match ($brokenTarget) {
+			WorkflowRunner::TARGET_SOURCE_STACK => 'sein Quell-Stapel nicht mehr existiert',
+			WorkflowRunner::TARGET_TARGET_STACK => 'sein Ziel-Stapel nicht mehr existiert',
+			default => 'sein Board nicht mehr existiert oder für dich nicht mehr verfügbar ist',
+		};
+	}
+
 	/**
 	 * One-off notice that a workflow was switched off because the board or
 	 * stack it points at is gone.
@@ -143,11 +157,7 @@ class NotificationMailer {
 			return;
 		}
 
-		$reason = match ($brokenTarget) {
-			WorkflowRunner::TARGET_SOURCE_STACK => 'sein Quell-Stapel nicht mehr existiert',
-			WorkflowRunner::TARGET_TARGET_STACK => 'sein Ziel-Stapel nicht mehr existiert',
-			default => 'sein Board nicht mehr existiert oder für dich nicht mehr verfügbar ist',
-		};
+		$reason = self::describeBrokenTarget($brokenTarget);
 
 		try {
 			$settingsLink = $this->urlGenerator->getAbsoluteURL('/settings/user/' . self::APP_ID);