Ask for visibility if group is platform (#242398)

## Summary

We were defaulting visibility to `private` if group not provided as cli
`--group` flag.
This is incorrect, since users can still choose `platform` group, and in
that case we need to ask for desired visibility.

Author: gsoldevila

packages/kbn-generate/src/commands/package_command.ts

@@ -95,10 +95,6 @@ export const PackageCommand: GenerateCommand = {
     let group = flags.group as KibanaGroup | undefined;
     let visibility = flags.visibility as 'private' | 'shared' | undefined;
 
-    if (group !== 'platform') {
-      visibility = 'private';
-    }
-
     const license = flags.license as 'oss' | 'x-pack' | undefined;
     let calculatedPackageDir: string;
 
@@ -157,6 +153,10 @@ export const PackageCommand: GenerateCommand = {
           })
         ).group;
 
+      if (group !== 'platform') {
+        visibility = 'private';
+      }
+
       let xpack: boolean;
 
       if (!!license) {