[Improvement][Perf]: make ClassTypeDefinitions lazy and/or cached

[dkarlovi]

Improvement description

Currently, \Pimcore\Bundle\DataHubBundle\GraphQL\ClassTypeDefinitions::build is creating type instances for all classes on every request

data-hub/src/GraphQL/ClassTypeDefinitions.php

Lines 35 to 54 in f781127

	public static function build(Service $graphQlService, $context = [])
	{
	$db = Db::get();
	$listing = $db->fetchAllAssociative('SELECT id, name FROM classes');
	foreach ($listing as $class) {
	$id = $class['id'];
	$name = $class['name'];
	$objectType = new PimcoreObjectType($graphQlService, $name, $id, [], $context);
	self::$definitions[$name] = $objectType;
	}
	/**
	* @var string $name
	* @var PimcoreObjectType $definition
	*/
	foreach (self::$definitions as $name => $definition) {
	$definition->build($context);
	}
	}

but not all classes will be used. It would make sense to convert this to a lazy loaded version where the instance is only created when get() is called.

This build process is almost 40% of the runtime in trivial GraphQL queries.

[github-actions]

Thanks a lot for reporting the issue. We did not consider the issue as "Pimcore:Priority", "Pimcore:ToDo" or "Pimcore:Backlog", so we're not going to work on that anytime soon. Please create a pull request to fix the issue if this is a bug report. We'll then review it as quickly as possible. If you're interested in contributing a feature, please contact us first here before creating a pull request. We'll then decide whether we'd accept it or not. Thanks for your understanding.