[FIX] tools: always retrieve a langage on formatLang
[FIX] tools: always retrieve a langage on formatLang

- Since commit https://github.com/odoo/odoo/commit/f5cd483216af01001f44a41f7d48f042b9f56ff9
the method `_lang_get` doesn't fallback on a language if the asked language
isn't found.

This causes issues with `formatLang` that uses the language on the
context, which is the language set on the client browser (in most cases).

Meaning, if 'en_US' is the only installed language and a customer
has set his browser to `fr_FR`, when calling `formatLang` this will
crash since no language has been found and `format` on `res.lang`
requires a singleton.

closes odoo/odoo#35633

Signed-off-by: Toufik Benjaa (tbe) <c6f81aa4457266a65463c97406f59c8b81e8d7de@odoo.com>
ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo