Add registry backup & restore (#566)

Starting from this commit, Win11Debloat will automatically create a registry backup every time the script is run. This registry backup can be used to revert any registry changes made by the script.

Scripts/Helpers/Test-TargetUserName.ps1

@@ -0,0 +1,47 @@
+function Test-TargetUserName {
+    param(
+        [AllowNull()]
+        [AllowEmptyString()]
+        [string]$UserName
+    )
+
+    $normalizedUserName = if ($null -ne $UserName) { $UserName.Trim() } else { '' }
+
+    if ([string]::IsNullOrWhiteSpace($normalizedUserName)) {
+        return [PSCustomObject]@{
+            IsValid = $false
+            UserName = $normalizedUserName
+            Message = 'Please enter a username'
+        }
+    }
+
+    if ($normalizedUserName -eq $env:USERNAME) {
+        return [PSCustomObject]@{
+            IsValid = $false
+            UserName = $normalizedUserName
+            Message = "Cannot enter your own username, use 'Current User' option instead"
+        }
+    }
+
+    if (-not (CheckIfUserExists -userName $normalizedUserName)) {
+        return [PSCustomObject]@{
+            IsValid = $false
+            UserName = $normalizedUserName
+            Message = 'User not found, please enter a valid username'
+        }
+    }
+
+    if (TestIfUserIsLoggedIn -Username $normalizedUserName) {
+        return [PSCustomObject]@{
+            IsValid = $false
+            UserName = $normalizedUserName
+            Message = "User '$normalizedUserName' is currently logged in. Please sign out that user first."
+        }
+    }
+
+    return [PSCustomObject]@{
+        IsValid = $true
+        UserName = $normalizedUserName
+        Message = "User found: $normalizedUserName"
+    }
+}