Symfony 6 & 7 Compatibility, Refactorings for extendibility (#39)

* Refactoring Application.php, extracting the setup of the event handlers.
* Don't display empty tables.
* Widening the Symfony version constraints.
* Refactoring for Symfony 6x support and preparing the TextRenderer for being replaceable.
* Removing unused import
* Adding forgotten interface
* Support Symfony ^6.0 and ^7.0

Author: floriankraemer

composer.json

@@ -5,11 +5,11 @@
     "require": {
         "php": "^8.1",
         "nikic/php-parser": "^5.1",
-        "symfony/console": "^7.3",
-        "symfony/config": "^7.3",
-        "symfony/yaml": "^7.3",
-        "symfony/dependency-injection": "^7.3",
-        "symfony/messenger": "^7.3"
+        "symfony/console": "^6.0||^7.0",
+        "symfony/config": "^6.0||^7.0",
+        "symfony/yaml": "^6.0||^7.0",
+        "symfony/dependency-injection": "^6.0||^7.0",
+        "symfony/messenger": "^6.0||^7.0"
     },
     "autoload": {
         "psr-4": {