Currently e.g. syntax errors during the import are logged as
exceptions but they don't fail the loading / testing.
Update the loading using more modern loading APIs, in order to not
catch them at all (let them bubble up normally), and instead just
find *IF* a module has a tests submodule before trying to load
in (LBYL).
Fixes#80198closesodoo/odoo#97957
Signed-off-by: Xavier Morel (xmo) <xmo@odoo.com>