REG_SZ can also be empty

[wokis]

REG_SZ key values can also be empty. Currently they are marked with a This MultiString Value has a value of $null comment and generate a The Write-DSCString command was called but the parameters block is missing a property name error.

• If a REG_SZ value is $null the comment This MultiString Value has a value of $null shouldn't be added, unless a $null string value has some special mening to some security policies in which case the comment should be be changed to include string as well.

• If a REG_MULTI_SZ or REG_SZ value is $null we shouldn't generate the The Write-DSCString command was called but the parameters block is missing a property name error.

https://github.com/microsoft/BaselineManagement/blob/bc23b244f7ee379427be22da2b5d575df5a9b4e6/src/Parsers/GPO/Registry.ps1#L357

https://github.com/microsoft/BaselineManagement/blob/bc23b244f7ee379427be22da2b5d575df5a9b4e6/src/Helpers/Functions.ps1#L416

[wokis]

An example of a policy using an empty REG_SZ as its default value is the "Select when Quality Updates are received"(https://admx.help/?Category=Windows_10_2016&Policy=Microsoft.Policies.WindowsUpdate::DeferQualityUpdates) policy. Specifically the Software\Policies\Microsoft\Windows\WindowsUpdate\PauseQualityUpdatesStartTime key.