Pager should have getTotalResults method function

[crustamet]

#2954

/**
 * Returns the total count of the results.
 *
 * @param string|null $group
 *
 * @return integer
 */

public function getTotalResults(string $group = 'default'): int
{
	$this->ensureGroup($group);
	
	return $this->groups[$group]['total'];
}