The refactoring of the wysiwyg editor and 'html' field allows us to
move some of the code that was in web_editor but only used in website or
in mass_mailing. Some parts are still in web_editor but will be
moved at a later time.

When creating a banner using the web editor, the targeted image
appears centered in the editor but is aligned on the left in the
email.

The issue also happened with other alignment (left in a centered
widget, right, ...) for example on outlook 2007 and should be solved
with this changeset.

note: 12.0 version of #29214

opw-1904827
Co-authored-by: Nicolas Lempereur <nle@odoo.com>
closes #29954

Because we converted buttons into tables so inline buttons was
breaking into multiple lines so we need to add display inline and vertical align
properties in tables.

We allowed display property from mail sensitizer whitelist.

Because in this commit https://github.com/odoo/odoo/commit/cf15030ed09f7479f5b2701ba101a5bed71f7409
we use display property for align items

Because of outlook hack node was not find next sibling of current element.
Due to this only first button is transcoded into inline css.

- Email generated from mass mailing will have its own layout with internal css.
- strip_classes is removed from mail_message because mail client are now supporting
  internal stylesheet. we need it for make mail responsive.

mail: manually removed classes from incoming mail body

Because we removed strip_classes from mail message body field because we want to
allow classes in outgoing mail to make it responsive but classes are not removed
from incoming mails so here we manually removed classes from incoming mail.

opw-1836556

Since e94702d8 when transcoding an element for the purpose of sending it
by mail, if the element had:

 border-bottom-style: solid;

in the CSS resulting from classes, it would be simplified to:

 border-style: 0 0 solid 0;

which is wrong since 0 is invalid for border-style, the default being:

 none

opw-1852839
closes #25423