Pull Request for Issue ##42181 .

Summary of Changes

Adds a check to see if the symlink function is available in php before proceeding with the cli script to create a public folder and provide an informative error message

Testing Instructions

php .\cli\joomla.php site:create-public-folder

Actual result BEFORE applying this Pull Request

if the function is not available

php cli/joomla.php site:create-public-folder

Create a public folder
======================

 Please enter the absolute path to the public folder:
 > /home/webmaven/public_html/pubtmp6


In PublicFolderGeneratorHelper.php line 199:
                                                          
  Call to undefined function Joomla\CMS\Helper\symlink()  

Expected result AFTER applying this Pull Request

if the function is not available

 php8 cli/joomla.php site:create-public-folder

Create a public folder
======================

 Please enter the absolute path to the public folder:
 > /home/brian/public_html/ttt66
                                                                                                                        
 [ERROR] symlink() function is not enabled on the server. Please enable it to proceed   

Link to documentations

Please select:

• Documentation link for docs.joomla.org:

• No documentation changes for docs.joomla.org needed

• Pull Request link for manual.joomla.org:

• No documentation changes for manual.joomla.org needed