VesterTemplate.Test.ps1 - Verify $Desired is still $null when $Desired = $null

[midacts]

Currently if $Desired is $null, it skips testing whether the value is still $null.
Current

We should wait for #114 to be resolved, but i have been testing with this and it works:
https://gist.github.com/Midacts/3f6f3304dcfad54765f8faa11ecb05d8

It adds the check to make sure $null still equals $null inside of the It blocks Try statement.