Remove the package flow and related code.

[selanthiraiyan]

Listing the code that needs to be removed. This is not a definitive list and please remove other code if applicable.

• AIToneVoiceView
• AddProductFeaturesView and AddProductFeaturesViewModel #13106
• LegacyProductDetailPreviewView and view model
• Remove aboutProduct case from AddProductWithAIStep enum
• Package flow related view and view models

[dangermattic]

🚫 Please add a type label (e.g. type: enhancement) and a feature label (e.g. feature: stats) to this issue.