Improve app page with sorting, recommendations and more (#520)

Scripts/Helpers/CheckIfUserExists.ps1

@@ -0,0 +1,32 @@
+function CheckIfUserExists {
+    param (
+        $userName
+    )
+
+    if ($userName -match '[<>:"|?*]') {
+        return $false
+    }
+
+    if ([string]::IsNullOrWhiteSpace($userName)) {
+        return $false
+    }
+
+    try {
+        $userExists = Test-Path "$env:SystemDrive\Users\$userName"
+
+        if ($userExists) {
+            return $true
+        }
+
+        $userExists = Test-Path ($env:USERPROFILE -Replace ('\\' + $env:USERNAME + '$'), "\$userName")
+
+        if ($userExists) {
+            return $true
+        }
+    }
+    catch {
+        Write-Error "Something went wrong when trying to find the user directory path for user $userName. Please ensure the user exists on this system"
+    }
+
+    return $false
+}