[IMP] website*: clean sitemap

From now, you need to explicitely add sitemap=True if you want your controller
into the sitemap.

It's the default value, but if you forgot it, it will raise a Warning on runbot.
It will avoid wrong controller in sitemap and duplicate (empty) content.

From now, if your model contains a field website_id, the modelConverter for
sitemap will automatically add the domain:
   "[('website_id', 'in', (False, current_website_id))]"

It avoid redundant declaration and ugly url in redirect/rewrite view.

Migration: need to remove it from url_from in website.rewrite

task-2065018

closes odoo/odoo#39427

Signed-off-by: Jérémy Kersten (jke) <jke@openerp.com>