In an x2many sub view, the attribute "force_save" on a field
indicates that the field value must be saved, even if the field is
readonly. Before this commit, this attribute was ignored by the
new views. In the BasicRelationalModal, we only needed to propagate
this attribute to the fieldsInfo given to the BasicModel. In the
RelationalModel, we needed to take the attribute into account.
closesodoo/odoo#95396
Signed-off-by: Géry Debongnie <ged@odoo.com>