[FIX] sale_quotation_builder: checkout product w/ quote description

Current behaviour:
If we add a blockquote in the `website_description` of a product on
the e-shop, we cannot checkout the product. Silent HTTP 400 error
code, due to an exception raised by
https://github.com/odoo/odoo/blob/bf772181933ce5334da35c8368455963b2478399/odoo/fields.py#L1987-L1993



Expected behaviour:
You should be able to checkout products even if they have blockquote
in their `website_description`.

Steps to reproduce:
- Install eCommerce, sale_quotation_builder (issue is present only
  after installing sale_quotation_builder)
- On a product, with the website editor, add a `blockquote` to the
  description of the product > Save
- In a private browser window, as public user, visit the product on
  the e-shop and try to checkout with it.
- Observe there is no visible error, and we do not proceed in the
  checkout process.

Reason for the problem:
The exception mentioned above is triggered when there is a
difference between the html content that is saved in the DB and after
sanitization, meaning that someone with escalated privilege saved
the HTML content by overriding the sanitization with
`sanitize_overridable`. In our use case the only diff is the
presence of the attribute `data-o-mail-quote-node` which is removed
after the sanitization.

Fix:
This issue can be resolved two ways:
1) Adding `data-o-mail-quote-node` to the list of save attributes,
   meaning it will not be removed during the sanitization process.
   Since this is an attribute that we add on `<blockquote>` nodes,
   it can be considered safe, just like `data-o-mail-quote`.
2) Remove the attribute sanitization of the `website_description`,
   just like it is done in the website_sale module.
   Since the `website_description` and `quotation_description` are both
   computed from one-another, they should have the same sanitization
   level.
I am implementing both solutions, 1) because adding the attribute to
the safe list seems safe in general, and may prevent future
issues of this sort. 2) because it is the root cause of the issue,
since the bug is present only after installation of the
`sale_quotation_builder` module.

Affected versions:
- 16.0
- saas-16.1
- saas-16.2
- master

opw-3297237

closes odoo/odoo#120764

Signed-off-by: Xavier Morel (xmo) <xmo@odoo.com>

addons/sale_quotation_builder/models/sale_order_line.py

@@ -14,7 +14,7 @@ class SaleOrderLine(models.Model):
         store=True, readonly=False, precompute=True,
         sanitize_overridable=True,
         translate=html_translate,
-        sanitize_form=False)
+        sanitize_attributes=False)
 
     @api.depends('product_id')
     def _compute_website_description(self):

odoo/tools/mail.py

@@ -30,7 +30,7 @@ _logger = logging.getLogger(__name__)
 
 safe_attrs = clean.defs.safe_attrs | frozenset(
     ['style',
-     'data-o-mail-quote',  # quote detection
+     'data-o-mail-quote', 'data-o-mail-quote-node',  # quote detection
      'data-oe-model', 'data-oe-id', 'data-oe-field', 'data-oe-type', 'data-oe-expression', 'data-oe-translation-initial-sha', 'data-oe-nodeid',
      'data-last-history-steps',
      'data-publish', 'data-id', 'data-res_id', 'data-interval', 'data-member_id', 'data-scroll-background-ratio', 'data-view-id',