Add support for pytest8

[micdahl]

With pytest8, the file collection phase has changed: https://docs.pytest.org/en/8.0.x/changelog.html#collection-changes To take into account Odoo's name binding with "odoo.addons"-prefix, the OdooTestPackage and OdooTestModule classes use adapted functions to compute the module name.

Also "--odoo-ignore-env" option is introduced, as the USER environment variable is set on some linux systems per default, which causes problems as it automatically is used for the Odoo database name. With the --odoo-ignore-env option set, environment variables are ignored and the options given via config options are used.