Improve the _get_link_preview_from_url method to:
- Only load necessary data (only the <head> instead of
the whole page).
- Handle optional request session.
- Handle all image mimetypes.
- Add a fallback on the <title> tag when no og:title have
been found.
Moving the method out of the model to facilitate
its use as a tool.
Task-3234864
Part-of: odoo/odoo#122087