Do not require DenySettingsMode parameter for MG scoped deployment stacks with MG scoped underlying deployments

**Is your feature request related to a problem? Please describe.**
DenySettingsMode is required in MG scoped deployment stack New and Set cmdlets when underlying deployment is at MG scope, even though deny settings are not supported on MG scoped deployment stacks with MG scoped underlying deployments. The cmdlets require you to specify 'None' for the DenySettingsMode.

**Describe the solution you'd like**
Will discuss possible solutions if issue is upvoted enough.

**Describe alternatives you've considered**
N/A

**Additional context**
N/A