Adjust the names (script, sample folder, generator) to lang option

Created by: ackintosh

Description

e.g. php:

There is some non-prefixed (with php-) script/folder.

lang	script (./bin/)	sample folder	generator
php	php-petstore.sh	php	PhpClientCodegen.java
php-lumen	lumen-petstore-server.sh	lumen	PhpLumenServerCodegen.java
php-slim	slim-petstore-server.sh	slim	PhpSlimServerCodegen.java
php-silex	php-silex-petstore-server.sh	php-silex	PhpSilexServerCodegen.java
php-symfony	php-symfony-petstore.sh	php-symfony	PhpSymfonyServerCodegen.java
php-ze-ph	ze-ph-petstore-server.sh	ze-ph	PhpZendExpressivePathHandlerServerCodegen.java

openapi-generator version

current master

Suggest a fix/enhancement

It is better to prefix the files with php- to avoid users/contributors be confused. (e.g slim-petstore-server.sh => php-slim-petstore-server.sh in the example above)