[FIX] web_editor: ensure correct fonts are used

Since commit [1], the new tiktok icon is added to odoo but the
conversion of the css class into an image is not supported.

This commit ensures that the conversion is correctly handled.

Steps to reproduce:
- Open the mail marketing app
- Create a new mass mailing
- Insert an icon in the template, for instance type /image in the text
  and select the "Pictogram" tab
- Search for tiktok icon and insert it
- Send the mass mailing
- The icon will not be found in the mail

[1]: https://github.com/odoo/odoo/commit/515915b9

closes odoo/odoo#158266

X-original-commit: 0fa2ce8212077facace67a0072aa4ddebc9b55f0
Signed-off-by: Romain Derie (rde) <rde@odoo.com>

doc/cla/corporate/acsone.md

@@ -35,3 +35,4 @@ Xavier Bouquiaux xavier.bouquiaux@acsone.eu https://github.com/xavier-bouquiaux
 Maxime Franco maxime.franco@acsone.eu https://github.com/FrancoMaxime
 Marie Lejeune marie.lejeune@acsone.eu https://github.com/marielejeune
 Justine Doutreloux justine.doutreloux@acsone.eu https://github.com/jdoutreloux
+Laurent Stukkens laurent.stukkens@acsone.eu https://github.com/it-ideas