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/Features/BackupRegistryFeatureSelection.ps1

@@ -0,0 +1,22 @@
+function Get-FeatureId {
+    param(
+        [Parameter(Mandatory)]
+        $Feature
+    )
+
+    $featureId = [string]$Feature.FeatureId
+    if ([string]::IsNullOrWhiteSpace($featureId)) {
+        throw 'Selected feature is missing required FeatureId.'
+    }
+
+    return $featureId
+}
+
+function Get-RegistryBackedFeatures {
+    param(
+        [Parameter(Mandatory)]
+        [object[]]$Features
+    )
+
+    return @($Features | Where-Object { -not [string]::IsNullOrWhiteSpace([string]$_.RegistryKey) })
+}