Large form views (containing a lot of fields), e.g. the crm.lead
form view, take a while to render (~ 250 ms). Most form views
contain several (sometimes a lot) invisible fields (invisible="1"),
whose only purpose in the view is to be fetched, so that they can
be used to evalute domains and contexts.
This commit implements a trivial optimization of the form renderer,
which consists in skipping the rendering of those invisible fields.
With this change, we gain ~25% of rendering time on the crm.lead
form view.
closesodoo/odoo#54368
Related: odoo/enterprise#11875
Signed-off-by: Lucas Perais (lpe) <lpe@odoo.com>