feat(service): unify database and storage backups on one page

List service database schedules with volume backups, add a database
picker when creating scheduled DB backups from the service page, and
cover the unified table and create flow in tests.

resources/views/livewire/project/database/create-scheduled-backup.blade.php

@@ -1,4 +1,11 @@
 <form class="application-settings-form flex w-full flex-col gap-4" wire:submit="submit">
+    @if ($service)
+        <x-forms.listbox id="selectedDatabaseUuid" label="Database" :options="$databaseOptions"
+            empty-text="No databases in this service support scheduled backups." required />
+        @error('selectedDatabaseUuid')
+            <p class="text-xs text-error">{{ $message }}</p>
+        @enderror
+    @endif
     <x-forms.input placeholder="0 0 * * * or daily" id="frequency"
         helper="You can use every_minute, hourly, daily, weekly, monthly, yearly or a cron expression." label="Frequency"
         required />