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

[jiasli]

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 (microsoft/knack#209), but an easier solution would be to call handle_version_update after the logger is initialized.

[yonzhan]

upgrade