Only install PowerShell module if necessary

scripts/Common/Scripts/SoftwareManagement.ps1

@@ -102,3 +102,18 @@ function Test-PSPackage {
 
     [bool] (Get-Package $Name -ErrorAction SilentlyContinue);
 }
+
+<#
+    .SYNOPSIS
+    Checks whether a module with the specified name is installed.
+
+    .PARAMETER Name
+    The name of the module to check.
+#>
+function Test-PSModule {
+    param(
+        [string] $Name
+    )
+
+    [bool](Get-Module -ListAvailable $Name -ErrorAction SilentlyContinue);
+}