Fast S3 verify and snapshot commit; shorter runs list; durations with days

On S3, index files and the tree segments read back when a snapshot is
written are fetched 16 at a time through the storage's S3 client
(IBackend::getRanges(), getMany()). Blobs that follow each other in a pack
are read as one range on every location. The snapshot is written in a step
of its own and the run shows "commit" meanwhile. On a 1 TB production
repository the check went from about 4 hours to 3.5 minutes.

backup:status and the web interface list the runs of the last 7 days,
running ones and at least the newest 5; --all / "Show older runs" list
all. Durations of a day or more show the days.

tests/Unit/FormatTest.php

@@ -0,0 +1,17 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OCA\NgBackup\Tests\Unit;
+
+use OCA\NgBackup\Format;
+use PHPUnit\Framework\TestCase;
+
+class FormatTest extends TestCase {
+	public function testDurationShowsDaysFromOneDayOn(): void {
+		$this->assertSame('00:00:00', Format::duration(-5));
+		$this->assertSame('12:10:13', Format::duration(12 * 3600 + 10 * 60 + 13));
+		$this->assertSame('1d 00:00:00', Format::duration(86400));
+		$this->assertSame('1d 12:10:13', Format::duration(86400 + 12 * 3600 + 10 * 60 + 13));
+	}
+}