[IMP] Sales: onboarding

[FIX]improve domain and override create method in product attribute value.

[IMP]Added placehoder in comment field,seted create and delete false in tree view of attribute value

[IMP]Added form view for attribute values and bind with action

[REM]Removed unused code as per spec changed

[REM]Removed unused code for product attribute values and rechange placeholder for purchase.

[REM]Removed changed placeholder from website quote.

[IMP]Improved typo
just add one condition also like
lambda self, cr, uid, context: 'partner' if context is not None and context.get('is_company') else 'contact'