!!! TASK: Deprecate additional site kickstart generators and show helpful output for default afx case

```
neos-manufacture-90 git:(9.0) ✗ flow kickstart:site Vendor.Site
Created .../Document.Page.yaml
Created .../Document.Homepage.yaml

Create a new site based on the new package "Vendor.Site" by running the site create command
./flow site:create vendor-site Vendor.Site Vendor.Site:Document.Homepage
```

Author: mhsdesign

Neos.SiteKickstarter/Classes/Command/KickstartCommandController.php

@@ -15,6 +15,7 @@
 use Neos\Flow\Annotations as Flow;
 use Neos\Flow\Cli\CommandController;
 use Neos\Flow\Package\PackageManager;
+use Neos\SiteKickstarter\Generator\AfxTemplateGenerator;
 use Neos\SiteKickstarter\Service\SiteGeneratorCollectingService;
 use Neos\SiteKickstarter\Service\SitePackageGeneratorNameService;
 
@@ -62,27 +63,40 @@ public function siteCommand($packageKey): void
 
         $generatorClasses = $this->siteGeneratorCollectingService->getAllGenerators();
 
-        $selection = [];
-        $nameToClassMap = [];
-        foreach ($generatorClasses as $generatorClass) {
-            $name = $this->sitePackageGeneratorNameService->getNameOfSitePackageGenerator($generatorClass);
+        if (count($generatorClasses) > 1) {
+            // legacy custom additional generators installed, so we need to show the select box
+            $selection = [];
+            $nameToClassMap = [];
+            foreach ($generatorClasses as $generatorClass) {
+                $name = $this->sitePackageGeneratorNameService->getNameOfSitePackageGenerator($generatorClass);
 
-            $selection[] = $name;
-            $nameToClassMap[$name] = $generatorClass;
-        }
-
-        /** @var string $generatorName */
-        $generatorName = $this->output->select(
-            sprintf('What generator do you want to use? (<info>%s</info>): ', array_key_first($selection)),
-            $selection,
-            array_key_first($selection)
-        );
+                $selection[] = $name;
+                $nameToClassMap[$name] = $generatorClass;
+            }
 
-        $generatorClass = $nameToClassMap[$generatorName];
+            /** @var string $generatorName */
+            $generatorName = $this->output->select(
+                sprintf('What generator do you want to use? (<info>%s</info>): ', array_key_first($selection)),
+                $selection,
+                array_key_first($selection)
+            );
+            $generatorClass = $nameToClassMap[$generatorName];
+        } else {
+            // default happy case, only one generator which MUST be the afx default
+            $generatorClass = AfxTemplateGenerator::class;
+        }
 
         $generatorService = $this->objectManager->get($generatorClass);
 
         $generatedFiles = $generatorService->generateSitePackage($packageKey);
         $this->outputLine(implode(PHP_EOL, $generatedFiles));
+
+        $this->outputLine();
+        $this->outputLine(sprintf('Create a new site based on the new package "%s" by running the site create command', $packageKey));
+
+        if ($generatorClass === AfxTemplateGenerator::class) {
+            $guessedSiteName = strtolower(str_replace('.', '-', $packageKey));
+            $this->outputLine(sprintf('./flow site:create %1$s %2$s %2$s:Document.Homepage', $guessedSiteName, $packageKey));
+        }
     }
 }

Neos.SiteKickstarter/Classes/Generator/AfxTemplateGenerator.php

@@ -24,6 +24,7 @@
 /**
  * Service to generate site packages
  *
+ * @internal
  */
 class AfxTemplateGenerator extends GeneratorService implements SitePackageGeneratorInterface
 {

Neos.SiteKickstarter/Classes/Generator/SitePackageGeneratorInterface.php

@@ -13,6 +13,9 @@
  * source code.
  */
 
+/**
+ * @deprecated with Neos 9. Custom generators for "kickstart:site" are discouraged.
+ */
 interface SitePackageGeneratorInterface
 {
     /**

Neos.SiteKickstarter/Classes/Service/FusionRecursiveDirectoryRenderer.php

@@ -15,6 +15,9 @@
 
 use Neos\Flow\Annotations as Flow;
 
+/**
+ * @internal
+ */
 class FusionRecursiveDirectoryRenderer
 {
     /**

Neos.SiteKickstarter/Classes/Service/SimpleTemplateRenderer.php

@@ -13,6 +13,9 @@
  * source code.
  */
 
+/**
+ * @internal
+ */
 class SimpleTemplateRenderer
 {
     /**

Neos.SiteKickstarter/Classes/Service/SiteGeneratorCollectingService.php

@@ -17,6 +17,9 @@
 use Neos\Flow\Annotations as Flow;
 use Neos\SiteKickstarter\Generator\SitePackageGeneratorInterface;
 
+/**
+ * @internal
+ */
 class SiteGeneratorCollectingService
 {
     /**

Neos.SiteKickstarter/Classes/Service/SitePackageGeneratorNameService.php

@@ -17,6 +17,9 @@
 use Neos\Flow\Annotations as Flow;
 use Neos\SiteKickstarter\Generator\SitePackageGeneratorInterface;
 
+/**
+ * @internal
+ */
 class SitePackageGeneratorNameService
 {
     /**