Add comprehensive test suite, fix minor issues, rename function and file names to match approved verbs (#708)

Scripts/Helpers/Generate-AppsList.ps1

@@ -0,0 +1,23 @@
+<#
+    .SYNOPSIS
+        Builds the validated application-removal list from the Apps parameter.
+#>
+function Generate-AppsList {
+    if (-not ($script:Params["Apps"] -and $script:Params["Apps"] -is [string])) {
+        return @()
+    }
+
+    $appMode = $script:Params["Apps"].toLower()
+
+    switch ($appMode) {
+        'default' {
+            $appsList = Import-AppsFromFile $script:AppsListFilePath
+            return $appsList
+        }
+        default {
+            $appsList = $script:Params["Apps"].Split(',') | ForEach-Object { $_.Trim() }
+            $validatedAppsList = Get-ValidatedAppList $appsList
+            return $validatedAppsList
+        }
+    }
+}