[4.4] Fix Sample data installation, fix finder helper addContentType null value

[Fedik]

Pull Request for Issue # .

Summary of Changes

Helper::addContentType() allows null for mime, however $db->quote() does not. Same as https://github.com/joomla/joomla-cms/pull/43051 but for 4.4

Testing Instructions

Use PHP 8+, set error reaporting to Maximum. Set DB driver to use MySQL PDO ~~On clean installation, try install "Blog Sample Data"~~

Run following code (example in index.php of the template):

$name = uniqid(); // Imitating a new content type name, can be any string
var_dump(Joomla\Component\Finder\Administrator\Indexer\Helper::addContentType($name));

Actual result BEFORE applying this Pull Request

PHP warning Deprecated: PDO::quote(): Passing null to parameter 1 ($string) of type string is deprecated

Expected result AFTER applying this Pull Request

No warning

Link to documentations

Please select:

• [ ] Documentation link for docs.joomla.org:
• [x] No documentation changes for docs.joomla.org needed
• [ ] Pull Request link for manual.joomla.org:
• [x] No documentation changes for manual.joomla.org needed