[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
We have used this xml_id to avoid duplication of records if we don't use this id then it will add that particular record once again which is already exist.