[FIX] base: translations when dev-mode is enabled

When computing the `arch` from the arch_db, the field gets translated
as a matter of course as `arch_db` is a stored field with a
translation method. This means `arch` is assumed to be in the proper
language in the cache.

However when reading from the filesystem (dev=xml) this is not the
case, and the view XML ends up untranslated.

Fix the issue by applying the translation function from arch_db onto
the stuff we got from the filesystem.

Note: under the assumption that we *do not* want to store translated
archs in arch_db, explicitly set the lang to None when resetting
views.

Task 2059557

closes odoo/odoo#50389

Signed-off-by: Xavier Morel (xmo) <xmo@odoo.com>