Investigate missing argument completer for certain enums

Is your feature request related to a problem? Please describe.
Enum properties should have argument completer for their values. Some enum parameters such as New-MgBetaIdentityGovernanceLifecycleWorkflow -DisplayName "PS Test AF" -Category ... (lifecycleWorkflowCategory) are missing argument completer. See https://github.com/azure/AutoRest/blob/master/Documentation/swagger-extensions.md#x-ms-enum.

Describe the solution you'd like
Argument complete should be provided for all enums. This is not a blocking issue as customers can still provide the enum values without an argument completer.

Describe alternatives you've considered
N/A

Additional context
N/A