Logs from `handle_version_update` is not shown in `--debug` mdoe

During the execution of `handle_version_update`, all `logger` invocations are not printed even if `--debug` is specified. This is because `handle_version_update` is called in `AzCli.__init__`, long before the logger is initialized.

This makes the troubleshooting of `handle_version_update` difficult.

Knack previously introduced `init_debug_log` and `init_info_log` to save `__init__` logs (https://github.com/microsoft/knack/pull/209), but an easier solution would be to call `handle_version_update` after the logger is initialized.