💡 [Feature]: Add possibility to add custom additional step

[Adam-it]

🎯 Aim of the feature

We should add some possibilities, preferably extending it as a setting for the extension, to allow devs to define their own additional setup options.
We could expose a setting in which users could manage a json array that will have a label and command. label will hold the string that will be present in the UI in the scaffolding form and command will be the npm command that should be executed after this option was selected.

example idea for a this kind of json object:

[
  {
    "label": "PnP JS SharePoint",
    "command": "npm install @pnp/sp"
  }
]

We should NOT allow to disable the pre-defined options

📷 Images (if possible) with expected result

No response

🤔 Additional remarks or comments

doing this change we should keep an eye out for this issue #216
if it is already done we should also add a option like visiblity that will allow to list out in as string array components that should have this option visible

parent issue: #185