Add allow_plugins setting since Composer 2.2.x

[peter279k]

Changed log

• Since using the Composer 2.2 version, the Composer plugin need to be set in the composer.json file. Otherwise it will cause the following exception message when running the composer update command:

.......
  dealerdirect/phpcodesniffer-composer-installer contains a Composer plugin w  
  hich is blocked by your allow-plugins config. You may add it to the list if  
   you consider it safe.                                                       
  You can run "composer config --no-plugins allow-plugins.dealerdirect/phpcod  
  esniffer-composer-installer [true|false]" to enable it (true) or disable it  
   explicitly and suppress this exception (false)                              
  See https://getcomposer.org/allow-plugins
.......