Delegate new tab creation to WebView (#3746)

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Task/Issue URL:
https://app.asana.com/0/856498667320406/1208699273169079/f
Tech Design URL:
CC:

**Description**:

Delegate new tab creation to WebView.

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**Steps to test this PR**:
1. Navigate to
https://privacy-test-pages.site/privacy-protections/referrer-trimming/
2. Check for referrer and how tabs behave.

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**Definition of Done (Internal Only)**:

* [ ] Does this PR satisfy our [Definition of
Done](https://app.asana.com/0/1202500774821704/1207634633537039/f)?

**Device Testing**:

* [ ] iPhone 
* [ ] iPad

**OS Testing**:

* [ ] iOS 15
* [ ] iOS 16
* [ ] iOS 17
* [ ] iOS 18

---
###### Internal references:
[Software Engineering
Expectations](https://app.asana.com/0/59792373528535/199064865822552)
[Technical Design
Template](https://app.asana.com/0/59792373528535/184709971311943)

DuckDuckGo/TabViewController.swift

@@ -2032,8 +2032,8 @@ extension TabViewController: WKNavigationDelegate {
         }
 
         if isNewTargetBlankRequest(navigationAction: navigationAction) {
-            delegate?.tab(self, didRequestNewTabForUrl: url, openedByPage: true, inheritingAttribution: adClickAttributionLogic.state)
-            completion(.cancel)
+            // This will fallback to native WebView handling through webView(_:createWebViewWith:for:windowFeatures:)
+            completion(allowPolicy)
             return
         }