Migration of data import code to BSK for re-use on iOS (#1184)

Task/Issue URL: https://app.asana.com/0/0/1209117022539264/f
iOS PR: duckduckgo/iOS#3855
macOS PR: duckduckgo/macos-browser#3768
What kind of version bump will this require?: Minor

**Description**:
Migration of data import code from macOS to BSK as needed for iOS 18.2
Safari data importing

Package.swift

@@ -75,7 +75,8 @@ let package = Package(
                 "UserScript",
                 "ContentBlocking",
                 "SecureStorage",
-                "Subscription"
+                "Subscription",
+                "PixelKit"
             ],
             resources: [
                 .process("ContentBlocking/UserScripts/contentblockerrules.js"),

Sources/BrowserServicesKit/DataImport/Bookmarks/BookmarksImportSummary.swift

@@ -0,0 +1,38 @@
+//
+//  BookmarksImportSummary.swift
+//
+//  Copyright © 2025 DuckDuckGo. All rights reserved.
+//
+//  Licensed under the Apache License, Version 2.0 (the "License");
+//  you may not use this file except in compliance with the License.
+//  You may obtain a copy of the License at
+//
+//  http://www.apache.org/licenses/LICENSE-2.0
+//
+//  Unless required by applicable law or agreed to in writing, software
+//  distributed under the License is distributed on an "AS IS" BASIS,
+//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//  See the License for the specific language governing permissions and
+//  limitations under the License.
+//
+
+import Foundation
+
+public struct BookmarksImportSummary: Equatable {
+    public var successful: Int
+    public var duplicates: Int
+    public var failed: Int
+
+    public init(successful: Int, duplicates: Int, failed: Int) {
+        self.successful = successful
+        self.duplicates = duplicates
+        self.failed = failed
+    }
+
+    public static func += (left: inout BookmarksImportSummary, right: BookmarksImportSummary) {
+        left.successful += right.successful
+        left.duplicates += right.duplicates
+        left.failed += right.failed
+    }
+
+}