Add fuzz target for previews (backport #3505)

[mergify]

This fuzz target mimics this code:

exiv2/app/actions.cpp

Lines 584 to 616 in 45c8b18

	int Print::printPreviewList() {
	if (!Exiv2::fileExists(path_)) {
	std::cerr << path_ << ": " << _("Failed to open the file") << "\n";
	return -1;
	}
	auto image = Exiv2::ImageFactory::open(path_);
	image->readMetadata();
	bool const manyFiles = Params::instance().files_.size() > 1;
	int cnt = 0;
	Exiv2::PreviewManager pm(*image);
	std::ostringstream os;
	std::ios::fmtflags f(os.flags());
	Exiv2::PreviewPropertiesList list = pm.getPreviewProperties();
	for (const auto& pos : list) {
	if (manyFiles)
	os << std::setfill(' ') << std::left << std::setw(20) << path_ << " ";
	os << _("Preview") << " " << ++cnt << ": " << pos.mimeType_ << ", ";
	if (pos.width_ != 0 && pos.height_ != 0)
	os << pos.width_ << "x" << pos.height_ << " " << _("pixels") << ", ";
	os << pos.size_ << " " << _("bytes") << "\n";
	}
	binaryOutput(os);
	os.flags(f);
	return 0;
	} // Print::printPreviewList
	Task::UniquePtr Print::clone() const {
	return std::make_unique<Print>(*this);
	}

I'll add it to OSS-Fuzz once it's merged.

---

This is an automatic backport of pull request #3505 done by Mergify.

[mergify]

Cherry-pick of d114ebb has failed:

On branch mergify/bp/0.28.x/pr-3505
Your branch is up to date with 'origin/0.28.x'.

You are currently cherry-picking commit d114ebbb.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	new file:   fuzz/fuzz-preview.cpp

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   fuzz/CMakeLists.txt

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally