[FIX] account,sale: Correct management of notifications to portal users

[FIX] sale: Don't display 'View quotation' button on email if no website
If the website module is not installed, the button 'View Quotation' will lead to the backend chatter page, which is not very useful in our case.
As the quotation is already attached in the mail as a pdf, just don't display the button if the website module is not installed

[FIX] account,sale: Don't send notif template to portal customers if no website

[FIX] account: Don't display 'View Invoice' button on email if no website
If the website module is not installed, the button 'View Invoice' will lead to the backend chatter page, which is not very useful in our case.
As the invoice is already attached in the mail as a pdf, just don't display the button if the website module is not installed

[FIX] website_sale: override get_access_action to redirect to my/invoices