fix(previews): Make thumbnail generation a bit more robust

[joshtrichards]

• Resolves: An unhandled exception has been thrown previewgenerator#501

Summary

Makes thumbnail generation a bit more robust for Office / MP3 / Image / Movie types.

Same thing is already being done for other types e.g. HEIC:

server/lib/private/Preview/HEIC.php

Lines 45 to 52 in c54038c

	$tmpPath = $this->getLocalFile($file);
	if ($tmpPath === false) {
	\OC::$server->get(LoggerInterface::class)->error(
	'Failed to get thumbnail for: ' . $file->getPath(),
	['app' => 'core']
	);
	return null;
	}

TODO

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)

[kesselb]

• Added the imports for LoggerInterface::class
• \OC::$server->get => \OCP\Server::get
• Squashed the commits