[FIX] web_editor: font>a colorize a change font color

If you change the color of a link with the editor without using the link
edition menu, this do not work (which might be expected), but if the
text outside the font had been colorized, the font will be applied
outside of the link only.

This is unexpected since if we have: "hello <a>cruel</a> world!", if we
select only "cruel" and change color, the change only happen to "hello"
and "world!".

With this changeset, an anchor in the ancestor prevent to use an
ancestor font tag to change color (which prevent the issue).

opw-2044551
closes #35862

Signed-off-by: Nicolas Lempereur (nle) <nle@odoo.com>